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Mind, Brain and Adaptation in the Nineteenth Century: Cerebral Localization and Its Biological Context from Gall to Ferrier
Robert M. Young
[ Contents | Preface | Introduction | Chapter: | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | Bibliography ]
EXPERIMENTAL SENSORY-MOTOR PHYSIOLOGY
AND THE ASSOCIATION PSYCHOLOGY
Pure empiricism does not lead us anywhere — not even to experience; much less, of course, to experiment. An experiment, indeed, is a question we put to nature. It presupposes, therefore, a language in which we formulate our questions; in other words, experiment is not the basis of theory, but only a way of testing it. Science does not result from an accumulation of facts; there are no facts that do not imply concepts.
Alexandre Koyré, 1954.
The Rise of Experimental Sensory-Motor Physiology
The developments from the end of Gall's work to the findings of Fritsch and Hitzig, and Ferrier, that inaugurated the classical period of cerebral localization involve five related themes: (1) the progressive acceptance and success of the experimental method and the concomitant abandonment of Gall's correlative method and cranioscopy. (2) The development of the view that the nervous system is organized in sensory-motor terms and the extension of this approach to progressively higher parts of the system. (3) The progressive application of the sensory-motor view to mental processes within the Lockean tradition of associationist psychology, involving both the abandonment of Gall's organology and his concepts of function in favour of the functions he opposed. These, in turn, were viewed as complexes of sensations, motions, and associations. Thus, both psychology and physiology adopted a uniform set of explanatory elements which left little place for cerebral organs or faculties. (4) The parallel continuation of the assumption of cerebral localization within phrenology and its combination with the above developments in physiology and psychology and with clinical findings, leading to the localization of muscular movements by Fritsch and Hitzig, and of muscular movements and the primary sensory modalities by Ferrier. (5) The development of a new biological context for psychological and physiological research-the theory of evolution. The early evolutionists applied the principle of continuity to mind and brain, but they failed to transcend the categories of function which they inherited from philosophical psychology.
Relations with the Orthodoxy: The Careers of Gall and Flourens
Gall and Flourens agreed that the brain is the organ of the mind, and Flourens gave Gall credit for establishing this point unequivocally.  Except for this fundamental thesis, it is difficult to think of an issue on which they did not disagree. It is true that Flourens thought Gall a good anatomist, but he pointed out that Gall's anatomical discoveries were irrelevant to his doctrine of the functions of the brain. Gall, on the other hand, finally granted the efficacy of Flourens' experimental methods for investigating irritability, sensibility, and motion but pointed out that such investigations held no promise of discovering the fundamental faculties or their organs. Thus, Flourens' methods and findings were irrelevant to the true aim of cerebral physiology as conceived by Gall. In view of their vehement opposition, it is ironic that it was Flourens, not Gall, who provided the first experimental demonstration of localization of function in the brain. He also provided the findings which dominated cerebral research for almost half a century, and methods which are still basic to neurophysiology. His findings eclipsed Gall's methods and assumptions and lent credence to his own. However, a more sophisticated use of Flourens' careful techniques, complemented by others, led eventually to the establishment of the very cortical localization of functions which Flourens opposed. Finally, the so-called 'new phrenology', which grew out of modified versions of Flourens' methods and Gall's assumption of cerebral localization, was based on a very different conception of the functions of the brain from that of either Gall or Flourens. They would have both opposed the conceptions of the sensory-motor localizers but for different reasons: Gall because their functions were not biologically significant and Flourens because they undermined his conception of the unity and independence of the mind. Neither would be sympathetic to the attempt to synthesize the whole of mental life and behaviour from associated sensations and motions, localized in the cerebral cortices. Of course, their protests were never heard. The conflict between Gall and Flourens antedates these developments by fifty years, and in contrasting them it will be convenient to consider their careers, methods, main findings, and assumptions in their contemporary context.
Jean-Pierre-Marie Flourens was born (1794) more than a generation after Gall (1758), and he lived until 1867, long enough to oppose Darwinism in his later writings. Gall's last work began appearing in the year that Flourens delivered his first experimental memoir (1822), and
1 See above, pp. 20-21.
2 See above, pp. 24n-25n.
Gall was able to include a detailed and vehement criticism of the new experimental methods in the later volumes. Flourens, on the other hand, presided over the demise of phrenology and contributed substantially to the criticism which discredited Gall and his followers by writing Examen de la phrénologie (1842) and De la phrénologie (1863). Whereas Gall was a controversial rebel whose work was never accepted as part of orthodox science, Flourens was a member of the Establishment, and his career was advanced at every stage by important patronage. Gall's public lectures in Vienna were proscribed by Emperor Francis I in 1802, on the grounds that they led to materialism and were opposed to the principles of morality and religion. Gall wrote a petition to the Emperor asking for a fair hearing, but it was denied, and he left Vienna in 1805. He and Spurzheim demonstrated their doctrine in over thirty cities in the next two years, and arrived in Paris in 1807 with an international reputations. Although Gall caused an immediate sensation, and his popular lectures were well attended, it was into society and not into scientific circles, that Gall and Spurzheim were welcomed. When they submitted a memoir on their work to the Institute in 1808, the commission which reviewed it produced an equivocal report on their anatomical findings and refused to consider their physiological doctrines at all. It is said that Napoleon took a personal interest in seeing that Gall was received coolly by the orthodoxy and even that Cuvier's initially sympathetic response to Gall's work was transformed under political pressure. Gall continued to have a large popular following and a successful medical practice (including many prominent patients). He became a naturalized French citizen in 1819 and lived in Paris until his death in 1828. In spite of his acknowledged contributions to neuroanatomy, his efforts in 1821 to obtain admission to the French Academy of Sciences (though supported by Geoffroy Saint-Hilaire) were unsuccessful. His following among prominent scientists came only after his death and was always tainted with unorthodoxy and even liberalism (which had no place in Gall's own political opinions). Finally, his books were placed on the Index, and he was refused a religious burial, though his orthodox religious beliefs were firm. It has been suggested that some of Gall's disfavour among orthodox scientists
1 Gall et al., 1838, p. 309. Cf. Gall, 1835, I, 19.
2 Gall et al., 1838, pp. 309-35, 336-9.
3 Gall, 1835, I, 65-66; Gall, 1835, VI, 119; Chevenix, 1828, p. 12; Temkin, 1947, p. 279.
4 Ebstein, 1924; Chevenix, 1828, p. 16. Ackerknecht and Vallois, 1956, p. 10.
5 Tenon et al., 1809.
6 Chevenix, 1828, pp. 15-16; Gall, 1835, I, 25; Gall, 1835, VI, 239-45; Ackerknecht and Vallois, 1956, pp. 10, 38, Temkin, 1947, pp. 300-13.
can be explained by his habit of speaking sensationally to popular audiences for a fee rather than confining his efforts to gaining the respect of the scientific community. Gall justified his practice as a means of gaining funds to finance his research and the publication of his large work,[l] but one suspects that his vanity was also involved.
The contrast between Gall's fortunes and those of Flourens is almost total. When Flourens arrived in Paris he bore a letter of introduction to the doyen of French science, Georges Cuvier, and was immediately received into the company of the most eminent scientists. He began submitting memoirs to the Academy of Sciences when he was twenty-seven, and their reception by the Commission was as flattering and enthusiastic as that of Gall and Spurzheim had been flat and guarded. In fact, Cuvier, Portal, and Pinel sat on both commissions. This support set the stamp of approval on his work and was largely responsible for its favourable reception in the scientific world. Cuvier's patronage was quickly and amply justified by Flourens' work in the period 1822-24, and the young experimentalist received the newly established Montyon Prize in Experimental Physiology in both 1824 and 1825. Before he was thirty-five he was elected to a seat in the Academy of Sciences, again with Cuvier's support. Cuvier entrusted his protégé with his course of lectures on natural history at the Collège de France as well as his course in anatomy at the Museum in the Jardin des Plantes. When Cuvier died in 1832, Flourens was offered his professorship, but instead took up a chair in Comparative Physiology specially created for him. Finally, from his deathbed, Cuvier bequeathed to Flourens his post as one of the permanent secretaries of the Academy of Sciences, and this was confirmed by a vote a year later. His eloquent eulogy to Cuvier was the first of a distinguished number which were collected and published in three volumes in 1857. In 1838 Flourens was chosen as a deputy from his home arrondissement. Two years later he was received into the French Academy, and he took his seat as the successful rival of Victor Hugo, whose popularity in Paris was then at its height. In 1846 he was elevated to a peerage. He was first given the ribbon of the Legion of Honour in 1832 and rose to the grade of Grand Officer by 1859.
Flourens' honours were well-deserved. In a series of memoirs and books between 1819 and 1865 he made important contributions to all
1 Ebstein, 1924.
2 Olmsted, 1953, p. 292
3 Anon. 1824.
4 Olmsted, 1953, p. 294.
5 Ibid., p. 296.
6 Ibid., p. 298.
10 Ibid., p. 299.
11 Ibid., p. 290.
12 Ibid., p. 301.
the following topics: the functions of the cerebrum, cerebellum, medulla oblongata, and semicircular canals; the formation of bone and teeth; diseases in birds; respiration in fishes; trephining; and the use of chloroform as an anaesthetic. He edited the works of both Cuvier and Buffon, wrote numerous monographs, and took an active part in scientific debate and politics. From this active and prolific career, the aspect of his work which has brought him the most lasting recognition is his work on the nervous system. By the time he was forty, M. Mignet, Director of the French Academy, claimed that Flourens' work ranked with the contributions of Albrecht von Haller, the founder of modern physiology, and Bell and Magendie. What Haller did for the peripheral nerves and Bell and Magendic did for the spinal nerves, Flourens had done for the major divisions of the central nervous system: he had determined their functions by experiment.[l] The distinctions conferred on Flourens were due primarily to the memoirs which were collected and published in 1824 as Recherches Expérimentales sur les Propriétiés et les Fonctions du Système Nerveux dans les Animaux Vertébrés and expanded by two-thirds in the second edition of 1842.
In retrospect, Flourens' methods were more important to scientific progress than were his findings. Although many of his experimental results remain valid, others-and especially the assumptions which they supported-retarded cerebral research for almost half a century. It is for this reason that his methods, findings, and assumptions will be considered separately.
Flourens' Method: Experimental Ablation
Where Gall had confined himself to naturalistic observations and correlation, Flourens was firmly committed to the experimental method. Gall claimed that he waited patiently for what nature brought; Flourens' approach was more active: 'I picture to myself physiology, a probe in her hand, eagerly turning over unknown soil in order to discover there the sources of life, and to make them redound to the profit of humanity.'He grants the importance of observation as a necessary prerequisite to experiment, but alone it is insufficient: 'It is too complicated to be comprehensive and too limited to be truthful.' Experiment reproduces all that observation shows, but it goes further, joins isolated facts, completes them, and explains them.
1 Olmsted, 1953, p. 290.
2 Quoted in Ibid., p. 302.
3 Flourens, 1842, p. 248.
In a word, what observation has begun experiment finishes. In the study of natural phenomena, there is thus a time for observation and a time for experiment. At first when one only tries to ascertain the obvious circumstances of these phenomena, observation suffices: then one wants to penetrate further into both the intimate constitution and the hidden resources; this is the task of experiment.
Flourens was very attentive to Gall's technical objections to the experimental method, and he set out to overcome them in his conception of the task of cerebral physiology.
Everything, in experimental researches, depends on the method; because it is the method which gives the results. A new method leads to new results; a rigorous method to precise results; a vague method can only lead to confused results.
Thus, the method which I have employed: 1st isolate the parts; 2nd remove, when necessary, the entire parts; and 3rd always prevent the complication of the effects on the lesions due to the effects of effusions.
He criticizes his predecessors (Haller, Zinn, Lorry, Saucerotte, Rolando) repeatedly for failing to isolate the parts which they were removing. This imprecision led to the inconsistent results which had brought the experimental method into disrepute. Similarly, he was careful to avoid causing injury which would obscure the direct effects of his operations. He chose only young animals with tender bones, a strong constitution, and less developed meninges. In order to minimize blood loss further he exposed only the part on which he was operating and extended the lesion no farther than was necessary. Finally, he waited until the effects of the operation itself had worn off, and kept his animals alive as long as possible so that his observations would not be complicated by the effects of operative shock, swelling, and pressure.
His predecessors had relied largely on pricking, pinching, and compression. Flourens' method was more precise and led to unambiguous results. Cuvier had high praise for this advance in methodology.
When, for instance, the brain was compressed, it was not well known, on what point of the interior the compression had most strongly acted; when an instrument was passed into the brain, the depth to which it extended was not sufficiently examined, nor into what organ it had been introduced. M. Flourens objects, with some reason, to the experiments of Haller, Zinn, and Lorry: and he has endeavoured to avoid this difficulty by operating principally by means of ablation, that is to say, by removing, whenever it
1 Flourens, 1842, p. 248.
3 Ibid., p. 502. See below p. 231.
4 Ibid., p. 510.
5 Ibid., pp. vi, 252-4, 505-7.
6 Ibid., pp. vii-viii.
7 Ibid., pp. viii, 252-4.
8 Ibid., Chapter IX.
9 Ibid., pp. ix-x.
was possible, that particular part, the special function of which he wished to know.
Flourens did not originate the method of ablation. Luigi Rolando had reported results based on this method as early as 1809. However, it can be said that Flourens was the first to use it successfully, in his experiments on the cerebellum. Similarly, Flourens claimed that he was the first to remove all the cerebral lobes.
It was the dramatic success of Flourens' precise use of ablation which established this method as a standard part of cerebral research. It has since been refined and complemented by very sophisticated methods of electrical and chemical stimulation, and by recording the electrical activity of areas varying in size from a whole lobe to a single neurone. However, the authors of the standard compendium on the cerebellum could still say in 1958,
There is a natural tendency, which is perhaps stronger in our time, to stress the importance of new approaches and to forget experiments made with older techniques. We believe that it would be particularly dangerous to indulge in this trend in a monograph on the cerebellum. The historical perspective of the reader would first of all be seriously distorted. Moreover, all the refinements in stimulating and recording techniques will never supplant ablation experiments. In fact, it is only through extirpation experiments that we may hope to know the main features of cerebellar function and to evaluate, more or less quantitatively, the relative importance of the different types of functional activity of this organ. . . . Stimulation experiments and electrophysiological studies can direct and suggest points for attack by ablation experiments, but can never take their place.
It should be emphasized that this testimony to the utility of the ablation method does not provide unqualified support for Flourens' use of it. His findings on the cerebellum have remained valid. For practical purposes the function which he was investigating is unitary, and successive slices from an anatomically discrete structure provided him with trustworthy results. However, subsequent findings have not justified Flourens' method of ablating the cerebral hemispheres by successive slices. Gall rightly points out that this approach is contrary to the structure of the cerebrum. If some form of cerebral localization were valid, Flourens' slicing indiscriminately through the hemispheres would still result in increasing loss of all its functions as the slicing proceeded. 'The sole method of proceeding would be in conformity
1 Flourens, 1842, pp. 71-72.
2 Gall, 1835, VI, 125-6.
3 Flourens, 1842, p. 508.
4 Dow and Moruzzi, 1958, p. 7.
with the true organization of the brain. . . . He mutilates all the organs at once, weakens them all, extirpates them all at the same time.' Consequently, Gall concludes, a million experiments of this kind would have no demonstrative value for cerebral localization. Methods do indeed give the results.
Flourens maintains that 'the end and goal of all physiology and pathology' is 'to deduce the alteration of the parts from the alteration of the properties, and, reciprocally, the lesion of the properties from the lesion of the parts'. Where Gall's method had involved four variables (striking behaviour, faculty, cortical organ, and cranial prominence), Flourens considered the faculties to be already established and the cranial prominence irrelevant. Consequently, his method reduced to making inferences about the seats of faculties from changes in behaviour consequent upon cerebral lesions. He said, in effect: 'I removed this part, and the animal ceased to do that, so this must be the seat of the faculty of that.' His conclusions were often based on months of careful, daily observation of the post-operative behaviour of his animals which he carefully recorded in his journal.
From a modern point of view, however, his method was only half-experimental. That is, he controlled the physiological aspect of his experiments, but in the behavioural realm he was still a naturalist. He carefully excised a part of the brain and then waited to see what happened. There was no attempt to establish standard criteria for loss of function. It is true that Flourens conducted tests, but these were crude and unstandardized. For example, after removing both cerebral lobes in a hen, he reports the following observations on the senses, made five months after the operation:
I let this hen starve several times for as long as three days. Then I brought nourishment under her nose, I put her beak into grain, I put grain into her beak, I plunged her beak into water, I placed her on a shock of corn. She did not smell, she did not eat anything, she did not drink anything, she remained immobile on the shock of corn, and she would certainly have died of hunger if I had not returned to the old process of making her eat myself.
Twenty times, in lieu of grain, I put sand into her beak; and she ate this as she would have eaten grain.
Finally, when this hen encounters an obstacle in her path, she throws herself against it, and this collision stops her and disturbs her, but to collide with an object is not the same as to touch it....... She is collided with and she collides, but she does not touch.
1 Gall, 1835, VI, 165-6. See below, pp. 231-2.
2 Flourens, 1842, p. 57.
3 E.g., Flourens, 1842, pp. 87-92.
8 Ibid., pp. 90-1.
The process by which he draws conclusions from these observations is as follows:
One judges that an animal does not have a certain sense when it does not use that sense any more.
An animal does not see any more when it knocks against everything that is in its way; it does not hear any more when no sound changes its expression; it does not smell any more when no odour attracts or repels it; it does not taste when no flavour attracts or angers it; it does not feel, it does not handle, it does not touch, when it does not distinguish any object, bumps obstinately against anything, and walks or advances against everything indifferently.
His experiments on the senses lack rigour, but one has only formal reservations about the legitimacy of these relatively simple inferences from anecdotal evidence. However, he is quick to draw further conclusions which give rise to more serious reservations.
An animal which really touches a body, judges it; an animal which does not judge anymore therefore does not touch anymore.
Animals deprived of their cerebral lobes have, therefore, neither perception, nor judgment, nor memory, nor will: because there is no volition when there is no judgment; no judgment when there is no memory; no memory when there is no perception. The cerebral lobes are therefore the exclusive seat of all the perceptions and of all of the intellectual faculties.
His evidence provides no basis for these sweeping conclusions or for the categories of function which he uses without question.
This mixed method of controlled physiological manipulation and naturalistic observation of the resulting behavioural changes remained characteristic of cerebral research throughout the nineteenth century. It was not until 1898 that Thorndike introduced standard, quantitative tests into the study of animal behaviour, and it was another decade before Franz and then Lashley integrated these methods with brain research and made controlled experimentation a standard feature of physiological psychology. These methods are still being slowly extended to studies on humans. Finally, it can be said that the design of standard, quantitative, behavioural tests which isolate identifiable pieces of behaviour, that in combination are sufficient to characterize a given function, remains a task for the future.
A final reservation should be made about the inferences which Flourens drew from his ablations. He was working solely with animals and primarily with birds. In spite of the familiarity with comparative
1 Flourens, 1842, pp. 96-7.
2 Ibid., p. 97.
anatomy which he must have derived from his teaching, from editing the works of Buffon and Cuvier, and from his own experiments, he had no reservations about drawing sweeping inferences about the functions of the human brain from experiments on lower organisms. This had disastrous effects where motion was concerned, since, in fact, birds may have no motor cortex and if they do it is small enough to be easily missed.[l] After the role of the cortex in motion had been established, Ferrier granted the validity of Flourens' findings on birds but rejected their extension to higher organisms. More important, perhaps, the behaviour of Flourens' experimental animals did not require him to consider seriously the concepts of function which Gall had derived from his comparative studies on men and animals. As Gall rightly pointed out, 'these cruel experiments, when they are made on animals of an order comparatively low, are hardly ever conclusive for man. In chickens, pigeons, rabbits, guinea pigs, and even in newly born animals of a superior order, the whole animal life is not by any means under the dominion of the brain.’ He even doubts that lower functions could be better understood by this approach, though he grants that some doubtful results might be obtained on irritability, sensibility, functions of the viscera, voluntary motion, respiration, etc.
Problems and Main Results
The foregoing analysis of Flourens' method and its limitations provides a basis for the study of his own conception of his work and for an exposition of his main findings. In his first memoir to the Academy of Sciences he describes his approach with elegant simplicity. The nervous system is the origin of sensations and movements and the site of the principle which wills, perceives, remembers, and judges. Do these constitute a simple property or many? Do they reside in the same or different parts of the system? If different, which parts serve each? No one before, he claims, has addressed these issues by direct experiments.
The point of the question and the difficulty is only therefore to ascertain experimentally (for it is only thus that one can ascertain) which parts of the nervous system are used exclusively for sensation, which for contraction, which for perception, etc.
Obviously, only experiment on each part would show which parts are used exclusively for which property. I have therefore subjected to experiment,
1 von Bonin, 1960, p. ix.
2 Ferrier, 1890, pp. 5-8.
3 Call, 1835, III, 97-8. Cf. Hollander, 1909, pp. 10-11.
4 Gall, 1835, III, 98.
5 Flourens, 1842, pp. 1-2.
one by one and separately, the nerves, the spinal cord, the medulla oblongata, the quadrigeminal tubercles, the cerebral lobes and the cerebellum.
The problems which Flourens addressed, like the method which he employed, derive from a tradition very different from Gall's naturalism. They were both concerned with the functions of the nervous system, but Gall set out to find new categories of analysis, while Flourens drew on the established problems of experimental physiology. The starting point for Flourens' investigations was the work of Albrecht von Haller, who has been called 'the founder of modern physiology'. Haller was the author of the first modern handbook or systematic treatise in the field. 'The year 1757 may be regarded in a certain sense as a red letter year in the history of physiology, as marking an epoch, as indicating the dividing line between modern physiology and all that went before. It was the year in which the first volume of the Elementa Physiologiae of Haller was published, the eighth and last volume leaving the press in 1765.’ This judgement is based on the modern treatment given in the work in his approach to anatomy and minute anatomy, and physical properties and chemical composition (so far as this was known). It particularly refers to Haller's own careful observations and sound judgement.
Flourens' experiments on animal functions stemmed directly from the concepts of Haller's treatise on the sensible and irritable parts of animals (1753). Nordenskiöld describes Haller's treatise as follows:
In this investigation he first establishes the fact that the organs of the body are partly irritable, partly non-irritable; why this is so, science cannot discover; it can only show that it is so. As irritable (irritabilis) he mentions such a part of the body as contracts upon being touched; as sensible (sensibilis), again, he defines a part of the body, contact with which induces an impression in the mind. Which organs belong to the one or the other category is a question which can be answered only by experiment. The performing of such experiments on live animals Haller finds highly revolting, but in the interests of truth it cannot in this case be avoided.
Thus, Haller was a pioneer in physiological experiments on live animals in order to discover the functions of organs.
1 Flourens, 1842, p. 3.
2 Roget, 1838, II, 382; Nordenskiöld, translated Eyre, 1928, p. 238; Wolf, revised McKie, 1952, p. 469.
3 Boring, 2nd ed., 1950, p. 16.
4 Foster, 1901, pp. 204-5.
5 Nordenskiölk 1928, p. 236. Cf. Young, 1968, p. 256 and fn. 33.
In his footsteps there followed an increasing number of scientists who sought by means of experiment on live animals-that is, vivisections — to ascertain the course of events in animal life, both in the isolated organs and in groups thereof, to an every-increasing extent.[l]
His doctrine of irritability was a modification of a broader concept of Francis Glisson. Haller argued that muscles were irritable, while nerves were the source of all sensibility. Later developments of the concept of irritability broadened it into a general attribute of living matter, while the specific reaction of muscle gave rise to the narrower concept of contractility. The concept of sensibility became the modern concept of nervous excitability, according to which the function of the nervous system is the transmission of impulses which result in sensations, muscular contractions, and secretions.
Haller also conducted experiments on the brain and concluded that the cortex must feel, though no movements resulted when it was irritated. On the question of cerebral localization, he admits that some experiments and phenomena of disease do support it, as does anatomical evidence (e.g., the parts of the brain near the optic nerve are probably concerned with vision). However, he concludes that
Our present knowledge does not permit us to speak with any show of truth about the more complicated functions of the mind or to assign in the brain to imagination its seat, to common sensation its seat, to memory its seat. Hypotheses of this kind have in great numbers reigned in the writings of physiologists from all time. But all of them alike have been feeble, fleeting, and of a short life.
In his first experiments Flourens set out to reform the nomenclature of neurophysiology. A contemporary English expositor provides a convenient summary of his argument. He wanted to eliminate an ambiguity, whereby the nerves had been said to be 'irritable and sensible, though they are merely organs for conveying the impressions which are to call forth these properties elsewhere'. He begins with the phenomenon that when one pricks a nerve it leads to contraction of a muscle and to a sensation. These events are not the properties of the nerve itself.
1 Nordenskiö1d, 1928, p. 374.
2 See Foster, 2nd ed., 1924, pp. 284-8; Anon., 1824, p. 144; Brazier, 1959a, p. 13.
3 See Verworn, 1913, Chapter I.
4 Foster, 1924, p. 292.
5 Quoted in Ibid., p. 296.
6 Anon., 1824, p. 144.
The nerve has therefore the property of receiving a peculiar impression, which is conducted in both directions along its course, producing contractions at its extremities, and sensation somewhere at its origin in the great nervous centre, the brain and spine.[l]
Flourens proposed that the property, inherent in muscular fibres, of undergoing contractions under stimuli be called 'contractility'; that the property of experiencing sensations be called 'sensibility'; and that 'irritability' should refer to the property, possessed by nerves, of receiving impressions which give rise to sensation and motion without experiencing them. Flourens' first experiments derive directly from this reasoning. He ligated a peripheral nerve in two places and stimulated above, below, and between the ligatures. The nerve was neither contractile nor sensible but conveyed irritations concerned with these properties. The same results occurred when he divided the spinal cord in two places, but the cord showed the additional property of combining muscular contractions to produce coordinated movements of joints or limbs. He then goes on to seek to discover by experiment what parts of the nervous system have the property of irritability. In his laudatory review of Flourens' memoir, Cuvier summarizes the questions as follows:
1st from what points in the nervous system must artificial irritation set out in order to arrive at muscle;
2nd To what points in the system ought impressions be propagated in order to produce sensation;
3rd From what points voluntary irritation descends, and what parts of the system ought to remain intact in order to produce it regularly.
In addition to sensation and movement, the nervous system is the seat of perception and will. But do perception and will reside in the same portion as sensation, and sensation in the same portion as movement? Flourens points out that the question of whether or not these are separate faculties has been debated over the centuries and still awaits solution.
As a result of a very large number of experiments on different species (e.g., frogs, cocks, hens, pigeons, ducks, mice, moles, cats, dogs), some of which were conducted in response to Cuvier's criticisms of his first memoir, Flourens arrived at the following conclusions Connection
1 Anon., 1824, p. 144.
3 Ibid., pp 145-6
4 Flourens, 1842, p. 68.
5 Ibid., pp. x-xii.
6 Ibid., pp. 60-86, 147-9
7 Flourens' arguments are rambling and repetitions, and his conclusions are scattered throughout the thirty-two chapters of his book. The following summary is based on a close reading of the book, but it would be pointless to cite the numerous repetitions of his findings and conclusions.
of nerve with muscle is required for muscular contraction, and connection with the brain is necessary for perception. If the peripheral end of a severed nerve is stimulated it produces muscular contractions, whereas stimulation of the central end produces pain. Thus, the two orders of phenomena-sensation and muscular irritation-are distinguished.[l] Following Bell, he finds the same separation of functions between the anterior and posterior spinal nerve roots, and the central and peripheral parts of the transected spinal cord. He exposed the spinal cord from the sacrum to the cranium and up to the cerebral mass, and irritated successively higher parts. He found a point where muscular contraction ceased to be produced by laceration, pricking, and burning, and concluded that excitability (i.e., production of muscular contractions) is not a property of the whole system. Stimulation of the cerebral hemispheres, corpus striatum, corpus callosum, optic layers, and cerebellum produced no movement, whereas stimulation of the bigeminal and quadrigeminal tubercles, the medulla and all lower structures produced movements ranging from violent convulsions to simple muscular contractions. He concluded that the cerebral hemispheres do not immediately excite muscular contractions and that neither the cerebral lobes nor the cerebellum is effectively the direct origin of any nerve. Conversely, if he removed the cerebral lobes, the animal suffered a profound weakness, became lethargic and no longer moved spontaneously. When prodded it would move but in a purposeless way and soon settled back into its lethargic state.
This evidence (along with that on the cerebellum, cited in the preceding chapter) is the basis for Flourens' distinction between volition, muscular contraction, and coordination. The elements of muscular contractions are directly excited by the nerves; these are combined into movements by the nervous trunks, spinal cord, and medulla. Coordination of voluntary movements is the property of the cerebellum. Voluntary control-the will-is exclusively the property of the cerebral lobes. He concludes that the intellectual faculty of will is independent of the locomotor faculties, which, in turn, are independent of the principle of coordination. The will provokes movements but is not the direct cause of any.
1 Flourens, 1842, pp. 3-4.
2 Ibid., p. 9.
3 Ibid., pp. 16-17.
4 Ibid., pp. 17-23.
5 Ibid., pp. xiv and 19.
6 Ibid., p. 22.
7 Ibid., p. 239.
8 See above pp. 47-50.
9 Flourens, 1842, pp. xiii, 27-31.
10 Ibid., pp. xiii, 50.
11 Ibid., pp. 237-9. I am not here considering Flourens' work on the mechanism of respiration, the 'vital point' and the 'movements of conservation', all functions of the medulla. See Flourens, 1842, Chapter X.
In view of later developments in cerebral physiology, it is important to consider more closely Flourens' view that the hemispheres play no direct role in exciting muscular movements. A simple explanation of his path to this wholly erroneous conclusion has already been given: he worked primarily with birds, and uncritically extended his results to higher organisms. However, he also conducted experiments on mammals, and he explicitly considered paralyses due to cerebral lesions. These lesions produced profound weakness and paralysis, though these often passed away as the animal recovered from the operation. He discusses crossed and direct effects in paralyses and convulsions, and recognizes the long-established fact that the motor impairment from cerebral lesions is a crossed effect. However, in this case, he makes no inference from the effects of lesions to the function involved and refrains from implicating the cerebral lobes in motor functions. This can only be attributed to the combined effect of his negative results on cerebral stimulation and the preconceptions which will be considered presently. There can be no doubt that he held this view without reservation. It is one of his most oft-repeated conclusions. When Rolando reported muscular contractions resulting from stimulation of the hemispheres of a pig and concluded that the hemispheres contain a group of fibres producing voluntary movement, Flourens confidently replied that Rolando only appeared to have induced such responses. They were actually due, Flourens argued, to the conduction of the current to the structures which immediately excite muscular contractions. 'My experiments establish that the hemispheres of the brain do not produce any movement.’
From his experiments on sensory functions Flourens concluded that the nerves, spinal cord, medulla, bigeminal and quadrigeminal tubercles, and cerebral peduncles have the properties of conveying sensations, but that perception resides in none of these structures. He argues that each sense originates in the eminence which gives rise to its nerves (e.g., vision in the quadrigeminal tubercles and hearing in the nervous extension of the cochlea). The distinction which he made between sensation and perception was based primarily on the fact that animals whose cerebral lobes had been ablated still responded to sensory stimulation, but they gave no evidence of appreciating the quality or meaning of the sensation. They failed to recognize or avoid objects, or to care for themselves in any way unless prodded. It is extremely
1 Flourens, 1842, Chapter XVI.
2 Quoted in Walker, 1957, p. 103.
3 Flourens, 1842, pp. 450- 1. Cf. Gall, 1835, VI, 167-8.
4 Flourens, 1842, pp. 123-5.
difficult to follow Flourens' arguments on this issue, and subsequent research has not supported his exclusion of sensation from the hemispheres. Also, the two editions of his book differ on this matter, and it appears that he was inconsistent in the first edition, while he consistently excluded sensation from the hemispheres in the 1842 edition. However, the main lines of his position are unambiguous: sensation is distinguished from perception and intelligence. Perception and intelligence reside exclusively in the cerebral lobes. Ablation of a single lobe causes loss of sight in the opposite eye but the remaining lobe is sufficient for the preservation of intelligence. Ablation of both cerebral lobes leads to loss of all perceptions at once. The animal becomes lethargic and fails to exhibit the instincts peculiar to that species. It does not wish, remember, or judge. He even ventures the conclusion that such animals are deprived of their dreams.
Although Flourens' arguments about motion and will have been discussed here separately from those regarding sensation, perception, and intelligence, it should be emphasized that the sensory-motor distinction played no part in his view of the cerebral hemispheres. Although he localized different functions in different parts of the nervous system, he considered the hemispheres a unitary organ. Thus, he was an advocate of localization in the brain but not within the hemispheres themselves. He stresses the conclusion that if one cortical faculty is lost all are lost: the cortex is a unitary organ whose functions constitute a unitary faculty. Perception, intelligence, will, and all the subdivisions of these (memory, reasoning, judgement, desire, etc.) reside together in the hemispheres. Successive slicing of the cerebral lobes led to concomitant loss of all these faculties. If sufficient tissue remained, function would be restored, but if the ablation was carried too far the faculties remained permanently lost. Thus, while the nervous system had diverse parts with diverse functions, it acted in a unitary fashion, and within this grand unity the unitary cortex presided over lower functions. These views provided the basis for opposition to
1 The two editions should be compared systematically with a view to distinguishing the meanings of the term sensation in particular contexts. It appears from a partial comparison that Flourens substituted the term perception for sensation in the second edition wherever he was concerned with the functions of the cerebral lobes. See below, p. 213, and Boring, 1950, pp. 77-8.
2 Flourens, 1842, pp. xv, 16, 24, 34.
3 Ibid., pp. 131-2
4 Ibid., pp. xvi, 48-9.
5 Ibid., pp. 33
6 Flourens, 1846, pp. 32-3. Cf. Riese. 1949, p. 122
7 Flourens, 1842, pp. xvi, 244
8 Ibid., pp. 208, 235, 243
cerebral localization, and the historical precedent for modern doctrines of mass action and cortical equipotentiality.
Although Flourens worked primarily as an experimentalist until the publication of the second edition of his Recherches in 1842, in subsequent years he became increasingly concerned with the philosophical issues surrounding his work. In his eulogy of Flourens, Claude Bernard noted that after Flourens was elected to the French Academy in 1841, his work became 'a combination of philosophy, science and literatures.’ It is indicative of his convictions (and extremely convenient for present purposes) that the first book which he wrote in this new vein was a polemic against phrenology: Examen de la phrénologie (1842). This work makes explicit the assumptions which had led Flourens to make a radical distinction between the sensory and motor parts of the nervous system on the one hand and the seat of perception, intellect, and will on the other. It also explains the basis of his vehement opposition to Gall's physiological and psychological doctrines.
Flourens' experimental methods were certainly an advance on Gall's naturalism, and if this were the only issue between them, it would be pointless to consider Flourens' objections in detail. Similarly, Gall has no defence against Flourens' accusation that his anatomical discoveries are irrelevant to Gall's own doctrine of the functions of the brain. However, very basic issues are at stake in the conflict between their respective psychological views. It has been pointed out that Flourens granted that observation was a necessary prerequisite for experiment. Nevertheless, in his own work, Flourens made no attempt to determine by observation a set of psychological categories which were relevant to the adaptations of species and individuals to their respective environments. Such observations should have constituted an obvious prerequisite to his experiments, and Gall was quick to point this out. Before experimental ablations could bear fruit,
It would have been requisite to know what could be found, and what ought to be sought for, in the brain. It would also have been necessary, that the mutilators should be divested of every metaphysical prejudice; that they should have a detailed knowledge of the fundamental powers. Where is the physiologist, where, the anatomist, who has been able to follow this direction, and who has not wished to find generalities and abstractions?
1 See Zangwill, 1961.
2 Quoted in Olmsted, 1953, p. 291.
3 Flourens, 1846, pp. 70-4. Quoted above, pp. 24n-25n.
4 Gall, 1835, III, 99.
Flourens granted this point in principle, but there is no evidence that is research.
It should be acknowledged that Gall's concepts of function may have been inadequate and that his faculty psychology begged the interesting questions which his studies of human and animal behaviour had raised. However, his psychological categories had the merit of relevance and were certainly an advance over the medieval faculties of perception, memory, judgement, imagination, etc. Gall was quite right to point out that Flourens' doctrine could not explain the marked differences among individuals and among species. He was also right to object that, while Flourens may have advanced the study of the vital functions, he had completely ignored the 'special animal functions'-the different propensities, instincts, talents, sentiments, and determinate intellectual faculties.
Flourens' criticism of Gall's faculty psychology is valid in its own right, but it is more interesting for the evidence it provides of the real basis of his objections. He grants that men and animals show very different propensities, talents, etc.
No doubt of it. But what sort of philosophy is that, that thinks to explain a fact by a word? You observe such or such a penchant in an animal, such or such a taste or talent in a man; presto, a particular faculty is produced for each one of these peculiarities, and you suppose the whole matter to be settled. You deceive yourself; your faculty is only a word-it is the name of the fact-and all the difficulty remains just where it was before.
The authority with which he supports this point leads us to the basis of Flourens' objections.
There are in us as many faculties as there are truths to be known....... But I do not think that any useful application can be made of this way of thinking; and it seems to me rather more likely to be mischievous, by giving to the ignorant occasion for imagining an equal number of little entities in the soul.
The quotation is from Descartes, to whom Flourens turned for the arguments which support his objections to Gall. The book is dedicated to the Memory of Descartes. In the preface, Flourens says,
Each succeeding age has a philosophy of its own.
The seventeenth century enthroned the philosophy of Descartes; the
1 Flourens, 1842, pp. 250-1.
2 Gall, 1835, VI, 173-4.
3 Ibid., VI, 1, 165.
4 Flourens, 1846, p. 39.
5 Quoted in Ibid., p. 41.
6 Flourens, 1846, p. xi.
eighteenth that of Locke and Condillac; should the nineteenth enthrone that of Gall?[l]
I frequently quote Descartes: I even go further; for I dedicate my work to his memory. I am writing in opposition to a bad philosophy, while I am endeavouring to recall a sound one.
Later, in the body of the work, he expresses his supreme contempt for Gall: 'Descartes goes off to die in Sweden, and Gall comes to reign in France.’
Flourens' rejection of Gall's psychology is wholly based on Cartesian dualism and the doctrine of the unity of the soul.
'I remark here, in the first place,' says Descartes, 'that there is a great difference between the mind and the body, in that the body is, by its nature, always divisible, and the mind wholly indivisible. For, in fact, when I contemplate it-that is, when I contemplate my own self-and consider myself as a thing that thinks, I cannot discover in myself any parts, but I clearly know and conceive that I am a thing absolutely one and complete.’
Now here is the sum and the substance of Gall's psychology. For the understanding, essentially a unit faculty, he substitutes a multitude of little understandings or faculties, distinct and isolate.
Gall reverses the common philosophy. . . . According to common philosophy, there is one general understanding-a unit; and there are faculties which are but modes of this understanding. Gall asserts that there are as many kinds of peculiar intelligences as there are faculties, and that the understanding in general is nothing more than a mode or attribute of each faculty.
Flourens joins Gall in rejecting sensationalism. Faculties are derived from the soul, not the senses. However, he goes farther and rejects Gall's argument for the plurality of the faculties by analogy from the fact that each of the senses has its proper, distinct organ. He does not contest the innateness of the faculties. In fact, he points out that although Locke opposed innate ideas, he did not doubt that our faculties are innate. He maintains that the innate faculties are, after all, only the unitary soul itself, 'viewed under different aspects'.
Flourens' view of the hemispheres is a consequence of his psychological assumptions.
Gall's philosophy consists wholly in the substitution of multipliciy for unity. In place of one general and single brain, he substitutes a number of small
1 Flourens, 1846, p. xiii. (Translation corrected.)
2 Ibid., p. xiv.
3 Ibid., p. 96.
4 Ibid., p. 53. Cf. p. 57.
5 Ibid., p. 38. Cf. p. 45.
6 Ibid., pp. 53-4. Cf. p. 41.
7 Ibid., p. 27.
8 Ibid., p. 70 ff.
9 Ibid., p. 52.
brains: instead of one general sole understanding, he substitutes several individual understandings.
If the understanding is a unit, its organ must also act in a unitary fashion. He repeats his experimental evidence in support of the thesis that 'the cerebral hemispheres concur, by their whole mass, in the full and entire exercise of the intelligence'. Any qualification of the unity of the soul or its organs is, as Flourens sees it, equivalent to denying the existence of the mind or soul. To divide the functions of the soul among different parts of the brain is equivalent to materialism. He cannot allow Gall's tendency toward the position that 'Organization explains every thing'. He is especially opposed to Gall's contention that our awareness of God is dependent on material conditions. Flourens maintains that the activities of the soul 'are not results-they are powers, and primary powers of thought'. His opposition to the materialist tendencies in Gall's thought are connected with his belief that division of the soul entails fatalism. He will allow no hint of limitation of free will: 'Liberty is precisely the power to determine against all motive'.
Flourens is explicitly opposed to Gall's naturalistic methods and his willingness to look upon 'the outer man' and construct 'the inner man after the image of the outer man'. He ridicules Gall for going out among men and questioning them. He is unwilling even to transcribe some of Gall's conclusions which offend his view of the dignity of man's soul. 'The pen refuses to transcribe such things, which fortunately, however, are pure extravagances.' Thus, Flourens' advocacy of physiological experimentation is complemented by a complete unwillingness to apply the scientific method to the study of mental phenomena, and his philosophical assumptions dictate the interpretation which he puts on his physiological findings. He immensely improved standards of research on the physiological side but relied solely on introspection for his psychological views. It is his consciousness (supported by Descartes') which provides evidence of unity to oppose Gall's observations on multiplicity, and his consciousness which supports his spiritualism and doctrine of moral liberty against Gall's alleged materialism and fatalism. He cites Descartes' Meditations as authority
1 Flourens, 1846, p. 47.
2 Ibid., p. 34.
3 lbid., p. 58.
4 Ibid., p. 63.
6 Ibid., p. 42. Cf. pp. 45, 59.
7 Ibid., p. 42.
8 Ibid., p. 76.
9 Ibid., p. 65. Cf. pp. 62-3.
10 Ibid., pp. 123-4.
for turning all the senses aside and closing off all contact with his memories and the external world in order to learn about his true nature. He has nothing but ridicule for the methods which would eventually transform behavioural studies.
Men will always be looking out for external signs by which to discover secret thoughts and concealed inclinations: it is vain to confound their curiosity upon this point: after Lavater came Gall; after Gall someone else will appear.
Flourens was not prepared to submit the human character, the mind, or its organ to analysis. Their unity was a necessary basis of his beliefs about man's dignity and freedom. On the other hand, he was prepared to subject sensory-motor functions to close analysis, as long as the organ of mind was kept entirely separate from this analysis. Thus, the hemispheres were the seat of perception, will, and intellect, but played no role in sensation and motion. How the will acted upon the lower centres which caused muscular contractions, and how sensations reached the organ of perception and higher functions, remained a mystery, for there were supposed to be no nerves connecting them. This separation is, of course, anatomically false and physiologically absurd. Also, having granted that the brain is the organ of the mind, one would expect that Flourens would have no reason to hold back from accepting the implications of this view. However, he could go this far and no farther. The pattern which was set in his research remained characteristic of investigations on the hemispheres for several decades. However, his methods and his research on sensation, motion, and irritability provided the basis for the eventual extension of the sensory-motor paradigm to the hemispheres. The success of his methods in some areas gave strong support to his other findings and to his assumptions. However, later use of the methods would eventually lead to the setting aside of Flourens' assumptions and conclusions. His technical contributions, when freed of the essentially theological context in which he used them, would serve other assumptions equally well and, in fact, better.
Magendie, the Experimental Method, and the Spinal Nerve Roots
Gall described himself as a naturalist who waited patiently for the results of observation, and opposed this approach to philosophical speculation. Flourens coupled a view of himself as an experimentalist
1 Flourens, 1846, p. 95.
2 Ibid., pp. 95-6. Cf. Bergmann, 1956.
‘with a probe in his hand', with a strong penchant for defending preconceived philosophical dogmas. François Magendie gave the following description of his work:
Every one is fond of comparing himself to something great and grandiose, as Louis XIV likened himself to the sun, and others have had like similes. I am more humble. I am a mere street scavenger (chiffonnier) of science. With my hook in my hand and my basket on my back, I go about the streets of science, collecting what I find.[l]
He had no use for philosophy. In fact, he discussed it only once-in his first publication. When Magendie qualified in medicine in 1808 (aged 24), physiology and biological sciences generally were not counted among the exact sciences. They lacked both the foundations and the prestige of the Newtonian sciences of physics and astronomy. His first paper attributed the unsatisfactory state of physiology to the influence of the theory of vital properties of Xavier Bichat, which separated physiology from physico-chemical analysis. Vitalism led to despair over the stability and dependability of vital phenomena, and Magendie opposed this. Bichat maintained that
The instability of the vital powers, is the quicksand on which have sunk the calculations of all the Physicians of the last hundred years. The habitual variations of the living fluids, dependent on this instability, one would think should be no less an obstacle to the analyses of the chemical physicians of the present age.
He argued that vital phenomena were not reducible to the laws of physics and chemistry, considered these sciences 'wholly strangers to physiology', and even opposed such obviously useful analogies as that between hydraulics and the study of the circulation of the blood. Magendie had no quarrel with Bichat's distinction between vital and physico-chemical phenomena. In fact, he remained a believer in vitalism throughout his career. Rather, he rejected the counsel of despair which Bichat had linked with his vitalism. It was the belief that vital phenomena were not stable which had been quicksand to previous investigators. Magendie insisted that physiologists should believe that their phenomena were law-like and that the only way of showing this was by the experimental method.
1 Quoted in Foster, 1899, p. 40.
2 Olmsted, 1944, pp. 20-2.
3 See Bichat, new ed., 1962: Rosen, 1946; Nordenskiöld, 1928, pp. 344-51; Temkin, 1946.
4 Bichat, n.d. p. 82; cf. pp. 81-4.
5 Ibid., p. 83.
6 Ibid., p. 91.
After he had made his position clear, Magendie never published another paper which did not contain reports of experiments or observations. In fact, the sterile discussions of vitalism and other doctrines of the day so repelled him, that 'he was driven towards the other extreme, and arrived almost at the position of substituting experiment for thinking'. He did not use experiments to test hypotheses. 'He so to speak thrust his knife here and there, to see what would come of it.'
The extremity of his reaction, coupled with the success of its fruits, led to Magendie's recognition as the founder of the purely experimental school of physiology in France. His career can be seen as the embodiment of growing acceptance of the experimental method in physiology.
Magendie's first experiments were concerned with the effects of strychnine. They were pioneer efforts in experimental pharmacology. In 1813, he resigned his appointment in anatomy, abandoned his prospects in surgery, and turned exclusively to experimental physiology. His first physiological experiments were on the mechanisms of swallowing and vomiting. He gave the first course in the science of physiology as an autonomous discipline, 'not as a mere adjunct to anatomy or medicine'. In the period between 1813 and 1822, he came to be known as 'the only professional exponent of experimental physiology'.
In 1816-17 Magendie published Précis Élémentaire de Physiologie, which ‘set a new fashion in text-books by calling the attention of students of medicine to experiment as a source of scientific knowledge'. It replaced Richerand's text, which adhered to Bichat's vitalism and made no attempt to provide an account of contemporary experimental work. In the preface, he reiterated his purpose: to bring physiology to the stature of a natural science by doing what Galileo had done for astronomy.
It is not enough to IMAGINE or BELIEVE, as the ancients supposed, but to OBSERVE, and, above all, to INQUIRE by EXPERIMENTS.
The object of this work is to endeavour to change the state of Physiology in this respect; to lead it back to positive facts; in one word, to impart to that beautiful science the happy renovation which has taken place in the physical sciences.
Magendie was strongly advocating the experimental method in the same period that Gall was completing his life's work. The last volume of Gall's Anatomie was published in 1819, and the first volume of the
1 Olmsted, 1944, pp. 20-1, 30-4
2 Foster, 1899, p. 39. Cf. Temkin, 1946, p. 35.
3 Foster, 1899, p. 40. Cf. Nordenskiö1d, 1928, p. 376.
4 Merz, 1903, p. 384.
5 Olmsted, 1944, pp. 35-44.
6 Ibid., pp. 51 ff.
7 Ibid., p. 51.
8 Ibid., p. 75.
9 Ibid., p. 66.
11 Magendie, translated Revere, 1843, p. v.
12 Ibid., p. vi.
revised edition appeared in 1822. In 1821, Magendie began the first journal devoted to experimental physiology, the Journal de Physiologie Éxpérimentale (and, after Vol. 11) et Pathologie. The journal was well received, paid for itself, and appeared for ten years. This success was aided by Magendie's policy of accompanying articles on animal experiments with citation of hospital cases illustrating the principles involved. Consequently, it was popular with physicians.
In the same year (1821), the Academy of Sciences awarded its first Montyon Prize in Experimental Physiology. Magendie received 'very honourable mention', while one of his pupils won half the prize. When Corvisart, who had been Napoleon's physician and a supporter of Gall, died in the same year, it is significant of the changing climate that his seat in the Academy of Sciences went to the young experimentalist, Magendie, in preference to Chaussier, who had once helped Magendie obtain a promotion and who was, at seventy-five, a venerable and respected anatomist. Magendie rapidly rose to the position of arbiter of all things physiological, including the award of the Academy's prize. In fact, according to a disputed account by Flourens, it was Magendie's experiments that had led to the establishment of the prize. In any case, Magendie sat on the committee that awarded a gold medal to Flourens in 1824 and the Montyon Prize in 1824 and 1825. Beginning in i823 a rivalry seems to have developed between them, based on supposed trespasses into each other's experimental domain. It recurred until Magendie's death, and Olmsted suggests that 'it may have been partly in pique that Flourens always gave first credit to Bell in regard to the discovery of the functions of the roots of the spinal nerves’.
Magendie's biographer reports that he was vain, stubborn, and rash. His fiery temper made him unpopular and often stimulated criticism. He was extremely jealous, and resented the work of others, especially those who had anticipated his own discoveries. These traits were all exemplified in the prolonged Bell-Magendie controversy over priority in discovering the functions of the spinal nerve roots, which did no one credit. Nevertheless, he continued in a distinguished experimental
1 Olmsted, 1944, p. 84.
2 Ibid., p. 85.
3 Ibid., pp. 87-8.
4 Ibid., pp. 48-9.
5 Ibid., p. 130. Cf. pp. 87-8.
6 Ibid., pp. 124, 130.
7 Ibid., pp. 127, 130. Cf. pp. 247-9.
8 The role of Sir Charles Bell in the discovery of the functions of the roots of the spinal nerves will be ignored in this presentation because it is irrelevant for present purposes and because Bell, as has been shown, was not an experimentalist. It should be noted, however, that both Flourens and Mueller give primary credit to Bell. (Flourens, 1842, p. 13; Mueller, translated Baly, 1838, pp. 642-4.) A balanced view of the shares of credit is that of Merz: Bell discovered the law on primarily anatomical evidence; Magendie verified it in living animals. The thesis was not generally considered to be proved until after Mueller's experiments in 1831. (Merz, 1903, p. 384.) Liddell takes the same view (1960, pp. 48-54). For more adequate treatments of Bell's work see Gordon-Taylor and Walls, 1958; Carmichael, I926. Concerning the controversy, see Olmsted, 1944, pp. 92-122, 130.
career and had numerous honours bestowed on him. He made significant contributions to the study of neurophysiology, hydrophobia, the cerebrospinal fluid, the circulatory system, goitre, cowpox, cholera, public health, and (in collaboration with Bernard) respiration and digestion.
If one considers the names most prominently associated with the experimental method in physiology in France in the nineteenth century they are all seen to be closely related: Flourens, Magendie, Bernard, and Pasteur. Pasteur considered Bernard the master spokesman for the method. Bernard, in turn, was Magendie's pupil. When Flourens died, Bernard succeeded to his Chair at the French Academy in 1868, and became Chairman of the Committee awarding the prize for experimental physiology. Thus, it can be seen that Magendie exerted a massive influence in establishing the experimental method in physiology in the first decades of the century, and in training its most eloquent exponent in the later decades. Concomitant with the rise of the experimental method, there was a decline in the prestige of correlative and anecdotal and purely anatomical investigations.
The Functional Division of the Spinal Nerve Roots
In the June, 1822, number of Magendie's journal, he published a short paper entitled 'Experiments on the Functions of the Roots of the Spinal Nerves'. He reports that for some time he had wanted to try the experiment of cutting the posterior roots of the spinal nerves. Several attempts to do this had failed, because of the difficulty of opening the vertebral canal. However, when someone gave him a litter of eight pups, six weeks old, he made a fresh attempt. He succeeded in reaching and cutting the posterior roots.
I at first thought the limb corresponding to the cut nerves to be entirely paralysed; it was insensible to pricking and to the strongest pressures
1 See Olmsted, 1944, Chapters 8-13, and pp. 271-7.
2 See Olmsted and Olmsted, new ed., 1961, p. 14 and passim; Vallery-Radot, translated Devonshire, 1960.
3 Olmsted and Olmsted, 1961, p. 153.
4 The paper is translated and reprinted in Olmsted, 1944, pp. 100-2. The experimental method was having spectacular successes on at least two important issues that summer. At the same meeting of the French Academy of Sciences, where Magendie communicated his classical findings on the spinal nerve roots, Cuvier delivered his laudatory report on Flourens' experiments on the cerebrum and cerebellum. It was on July 22, 1822. (Ibid., p. 124.)
seemed to be immobile; but soon, to my great surprise, I saw it move in a very obvious manner, although sensibility was stir quite extinct in it. A second, a third experiment gave me exactly the same results; I began to regard it as probable that the posterior roots of the spinal nerves might very well have different functions from the anterior roots, and that they were more particularly destined for sensibility.
He had great difficulty in reaching the anterior roots in order to conduct the complementary experiment, but he finally succeeded.
As in the preceding experiments, I made the section only on one side in order to have a means of comparison. One can imagine with what curiosity I followed the effects of this section: they were not painful, the limb was completely motionless and flaccid, whilst it preserved an unequivocal sensibility. Finally in order that nothing might be left undone, I cut the anterior and posterior roots at the same time; there was absolute loss of feeling and movement.
After repeating these experiments on various kinds of animals, Magendie concludes:
I am content to be able to state positively today that the anterior and posterior roots of the nerves which arise from the spinal cord have different functions, that the posterior roots seem to be particularly destined for sensibility, while the anterior roots seem to be especially connected with movement.
This discovery was made independently by Charles Bell on anatomical grounds and came to be known as the 'Bell-Magendie Law'. The importance of this single discovery for the subsequent history of research on the nervous system cannot be overestimated. Indeed, the remainder of this study is primarily concerned with tracing the progressive application of the functional division between sensory and motor nerves to successively higher parts of the central nervous system until it provided a uniform explanatory principle in both physiology and psychology.
The significance of this discovery was immediately appreciated by an international audience. The Edinburgh Medical and Surgical Journal reviewed Magendie's findings, along with the experiments of Flourens, and remarked, 'The discoveries of Magendie are not less important or less extraordinary, than those [of Flourens] we have hitherto been considering'. Gall also ranked the discovery of Magendie with that of
1 Olmsted, 1944, pp. 100-1.
2 Ibid., p. 101.
3 Ibid., pp. 101-2.
4 Anon., 1824, p. 154.
Flourens; that is, he discounted it. He conducted a review of the evidence, found it hopelessly contradictory, and concluded that the relations between given nerves and the phenomena of sensation and motion, and like questions, 'I say, are as yet, beyond the reach of our knowledge'.[l] His only other references to the finding are slighting. It can be seen just how far and how rapidly the methods and assumptions of physiological research were moving away from Gall's approach. His evaluation must be compared with the general consensus: 'Within ten years physiologists were to agree that the difference in function of the roots of the spinal nerves had been established, and that this discovery was second only to that greatest of all landmarks in the history of physiology, Harvey's discovery of the circulation of the blood'. In 1842 Longet called it 'the most beautiful physiological discovery of modern times.’ Fifty years later, Meynert referred to it as 'the first fundamental thesis of neurophysiology'. Although Magendie continued to lecture and to do experiments on the nervous system throughout his career, his later work and his discoveries in other areas are overshadowed by this single finding. Indeed, the subsequent history of neurophysiology and psychology have been dominated by it. However, in i822, its full implications were far from being realized, as Magendie’s own work shows.
The Functions of the Brain
The Committee which had reviewed the 1808 memoir of Gall and Spurzheim issued the following summary of the state of knowledge of the nervous system:
Undoubtedly, we cannot expect a physiological explanation of the action of the brain in animal life, like that of the other viscera. In these the causes and effects are of the same kind. When the heart causes the blood to circulate, it is one motion which produces another motion: when the stomach converts the food into chyle, it is the heat, moisture, gastric juice, and slow compression of its muscular coat, which unite to produce, at the same time, a solution and trituration, greater or less, according to the species of animal, and nature of its food.
The functions of the brain are of a totally different order. They consist in receiving, by means of the nerves, and in transmitting immediately to the mind, the impressions of the senses; in preserving the traces of these impressions, and in reproducing them with greater or less promptitude, distinctness, and abundance, when the mind requires them for its operations, and when
1 Gall, 1835, VI, 184.
2 Ibid., VI, 200, 206.
3 Olmsted, 1944, p. 112.
4 Quoted in Liddell, 1960, p. 53.
5 Meynert, 1891, p. 166.
the laws of the association of ideas recall them; lastly, in transmitting to the muscles, always by means of the nerves, the desires of the will.
Now these three functions suppose the mutual, but always incomprehensible influence of the divisible matter and the invisible mind (moi); a hiatus in the system of our ideas never to be supplied, an eternal stumbling-block of all our philosophies. But there is another difficulty not necessarily connected with the former. We not only do not comprehend, and never shall be able to comprehend how any traces impressed on our brain can be perceived by the mind, and produce images in it; but however delicate our researches, these traces are in no way visible to our eyes, and their nature is perfectly unknown to us; although the effect of age and of disease upon the memory does not permit us to doubt of their existence, or of their seat.
It seemed, at least, that the action of the nervous system upon the organic life, would be more easily explained, as it is entirely physical, and we might expect, by means of investigation, to discover in this system some texture, some intermixture, or direction of parts which would render it more or less analogous to the vascular or secreting organs. There was especially no reason to doubt, that it would be possible to unfold their different portions, to assign their connections, their relations, and respective terminations, as easily as in the other systems.
This, however, has not happened. The texture of the brain, of the spinal marrow, and of the nerves, is so fine, so soft, that all that has been hitherto said of them is blended with conjectures and hypotheses; and the different masses which compose the brain are so thick, and have so little consistence, that the greatest dexterity is required to show all the parts of their structure.
In short, none of those who have examined the brain, have succeeded in establishing a rational and positive relation between the structure of that organ and its functions, even those which are most evidently physical; the discoveries hitherto made known with regard to its anatomy, are confined to some circumstances regarding the form, connections, or texture of its parts which had escaped the observation of preceding anatomists; and whenever any one has supposed that he had proceeded farther, he has only introduced, between the well known structure and its common effects, some hypothesis, scarcely capable of satisfying for a moment even the least sceptical minds.
This view, held by Cuvier, Tenon, Pinel, Portal, and Sabatier, that is, by some of the most eminent scientists of the day, has been quoted in full because it provides an excellent statement of the position when Magendie began his researches on the nervous system. It should be recalled that Gall's work was primarily psychological and provided no basis for changing the prevailing opinion. Magendie, on the other hand, soon showed that something could be learned about the functions of the nerves by the experimental method. When he turned to the higher
1 Tenon, et al., 1809, pp. 38-9. Cf. below p. 208.
functions of the nervous system, it was legitimate to expect something equally exciting to result from the combination of his positivist principles and his experimental skill, and his initial approach was extremely promising.
The most sublime features of the human character are intelligence, thought, the passions, and that admirable faculty by which we are enabled to direct our movements, and communicate by speech. These phenomena are dependant upon the brain, and are designated by many physiologists as the cerebral functions. Other physiologists, sustained and inspired by religious creeds, regard them as belonging to the soul, a being derived from the Divine essence, of which immortality is one of the attributes. It would not be becoming in us to undertake to decide here between these two modes of contemplating this important subject; our object is science, not theology. Besides, we do not pretend to explain the acts of the understanding or the instincts; our object is to study them, and to demonstrate the physiological connection they may have with the brain generally, or with certain of its parts.
In this way he hopes to avoid the errors others have made. He considers the phenomena of the human understanding in the context of the physiology of the encephalon.
Whatever may be the number and diversity of the phenomena which pertain to the human understanding, however different they may appear from the other phenomena of life, and though they may be evidently dependent upon the soul, it is indispensable to consider them as the result of the action of the brain, and not to distinguish them, in any way, from other phenomena, which are dependent on organic action. Indeed, the functions of the brain are absolutely governed by the same general laws as the other functions.
They develop with age and are modified by experience and disease.
In a word, like every other organic action, they are not susceptible of explanation by us, and in investigating them, laying aside hypothesis, we must be governed by observation and experience alone. It is also necessary to guard ourselves against the impression that the study of the functions of the brain is more difficult than that of the other organs, and that it belongs exclusively to metaphysics. By adhering rigorously to observation, and scrupulously avoiding all explanations or conjectures, this study becomes purely physiological.
These statements appear to be the preamble to the studies which the Committee considered impossible, and the realization of some of the hopes which Gall clearly enunciated but could not himself fulfil: the
1 Magendie, 1843, pp. 135-6.
2 Ibid., p. 146.
investigation of the physiological bases of mental and behavioural phenomena.
However, when Magendie goes on to specify what he means by the 'physiological' study of the understanding, it becomes clear that the 'hiatus' mentioned by the Committee is still very much in evidence.
Perhaps it is even easier than many of the other faculties, from the facility with which we are enabled to produce and examine its phenomena, inasmuch as we have only to turn our attention upon ourselves, to listen or think, so that the phenomena may be subjected to our observation.
Granted, there are difficulties in this study, since we cannot directly know the thoughts of others.
But however this may be, the study of the understanding has not heretofore been considered as constituting an essential part of physiology. One science is specially devoted to this, and is called ideology. Persons desirous of examining this interesting subject in extenso, may consult the works of Bacon, Locke, Condillac, Cabanis, and, especially, the excellent work of M. Destutt de Tracy, entitled 'Elements of Ideology'. We shall confine ourselves to some of the fundamental principles of this science.
Magendie considers mental phenomena to be functions of the brain in principle and argues that their study is, like the study of any other organ, part of physiology. However, in his actual analysis, he reverts to the sensationalism of Condillac, and his contemporary disciples, Cabanis and Destutt de Tracy. 'Ideology' was a term invented by Destutt de Tracy. The Idéologues argued that ideas were merely compounds of sensations and saw the end of their enquiries as the analysis of ideas into their constituent sensations. This was supposed to supplant metaphysics. Although de Tracy claimed that 'Ideology is part of Zoology’, it is clear that its methods and assumptions were far from those that Gall had advocated for a biological science of psychology and which, suitably modified, would later be appreciated as important aspects of evolutionary biology.
The experimental method which Magendie applies to the spinal cord is replaced by the introspective and analytic approach which Gall had attempted to transcend by means of naturalistic observation of the behaviour of animals and men. The functions which he investigates and which he attempts to relate to the nervous system are the
1 Magendie, 1843, p. 146.
2 Ibid., p. 147.
3 Cf. Temkin, 1946, pp. 13, 14, 16, 24.
4 Boas, 1925, p. 24.
5 Ibid., pp. 4-5.
6 Ibid., p. 24.
7 Quoted in Ibid., p. 25.
8 Cf. Temkin, 1947, p. 291.
9 See Rosen, 1946, p. 334.
traditional normative categories of philosophical analysis: sensibility, memory, judgement, and desire or will. He makes no attempt to consider whether or not these categories are adequate for the explanation of experience and behaviour. While he considers thought a function of the brain, he does not enquire into the functional role of thought in the lives of organisms. Thus, in practice, his psychology had stronger links with metaphysics than with biology.
Although the terms 'sensation' and 'motion' appear in both his work on the spinal cord and his discussion of the functions of the brain, he thought of these as two orders of phenomena and did not attempt to integrate them into a unified view. This was the task of the halfcentury which followed his initial discovery. Magendie's own work exemplifies the traditional analysis in one part of his work on the nervous system, while in another he provides the experimental finding which eventually transformed the philosophical sensationalism of the Idéologues into an experimental sensory-motor psychophysiology.
Magendie's treatment of Ideology was at least an advance on Condillac, who had made no attempt to specify the material basis of his sensationalism. Cabanis had set out to correct this omission, and investigated the structure of the sense organs and the physiological conditions of mental processes, including how they varied with age, sex, temperament, diet, and so on. He had also stressed the importance of internal sensations in addition to the five external senses. Magendie's treatment of the senses is an exposition of the ideas of Cabanis and involves no new findings.
Magendie turns from an exposition of the senses to an analysis of the intellectual phenomena for which they were the sole source.
The innumerable phenomena which constitute the human understanding (the human understanding has been called the spirit, the faculties of the soul, intellectual faculties, cerebral functions, etc.) are but modifications of the faculty of perception. When we examine them with attention, we shall find no difficulty in confirming this observation, the truth of which is generally admitted by modern metaphysicians.
We may divide the faculty of perception into four principal modifications: 1st. Sensibility, by which we receive impressions from within or from without. 2nd. Memory, or the faculty of reproducing impressions or sensations previously received. 3rd. The faculty of perceiving the relation between sensations or judgment. 4th. Desire or Will.
1 Cabanis, 1805; Boas, 1925, pp. 4-5. Cf. Lange 1925, II, 242-3; Merz, 1903, pp. 470-2.
2 Temkin, 1946, pp. 25-6.
3 Magendie, 1843, pp. 112-15.
4 Ibid., p. 147.
These four are the 'simple faculties of the mind'.'It is the combination and reaction of these faculties upon each other which constitutes the understanding of man and the higher order of animals.' Magendie proceeds to explain each of them and to attempt to specify their relations with the nervous system. In following the details of his discussion, one is struck by the vagueness of his analysis of the higher functions, compared with the elegance and simplicity of his classical experiment on the spinal nerve roots.
I. Sensibility has two modes. The first is unperceived and is the effect of a body impinging on the senses. 'In order for a perfect sensation to exist, it is necessary that the brain should perceive the impression received by it. An impression thus perceived is called, in ideology, a Perception, or idea.' The parts of the nervous system with which sensibility is most particularly connected are the posterior roots of the compound nerves and the superior branch of the fifth cranial nerve (trigeminal). 'I have shown, by experiment, that if these nerves are divided, the sensibility of the parts to which they are distributed is extinguished. Experiment has equally informed me, that if we divide the posterior fasciculi of the spinal cord, the general sensibility of the trunk is abolished'. Similarly, cutting the fifth pair of cranial nerves abolishes sensibility on the head, the face and its cavities. The evidence available to Magendie from his own experiments and those of others precluded the extension of the nervous basis of sensibility to the brain, except for the sense of sight. Ablation of the cerebrum abolishes sight, as Flourens and Rolando had shown, but ablation of the cerebrum or cerebellum involves no loss of odours, tastes, and sounds. Thus, while he saw the brain as the organ of the understanding, it was a mystery how it was related to most of the primary sensory modalities, the supposed source of all its operations.
2. Memory is the reproduction by the brain of recently acquired ideas, while recollection is the analogous function for more distant ideas. Magendie grants Gall's thesis that there are different kinds of memory for words, places, forms, music, and so on, and that these may manifest themselves individually to a striking degree and be selectively diseased. However, he denies the implication Gall drew from this.
1 Magendie, 1843, p. 151.
3 Ibid., p. 147.
4 Ibid., p. 148.
5 Ibid., p. 149.
6 Ibid., cf. p. 145. It will be recalled that Flourens considered the brain the seat of perception of all sensory modalities.
7 Ibid., p. 149.
Generally, in these cases, after death, lesions are found to a greater or less extent in the brain or medulla oblongata. But morbid anatomy has not established a direct and constant relation between the diseased part and the kind of memory abolished, so that we are still ignorant if there exists any part of the brain which is more particularly destined to the exercise of memory.
3. The principle of association was not explicitly recognized as an important factor in the psychological assumptions which Magendie adopted from the Idéologues, but the role played by association in the English tradition is served by the faculty of judgement. 'There can be no doubt that judgement is the most important of the intellectual faculties. . . . All our knowledge is the direct result of the faculty of judgement. To form a judgement is to establish a relation between any two ideas, or collections of ideas. . . . A series of judgements connected together constitutes reasoning'. The quality of one's judgement is 'the result of organization. It is impossible to change in this respect; we must remain as nature has formed us.’ 'We are ignorant of the part of the brain which is the particular seat of judgement. It has been long believed to be in the hemispheres, but nothing directly proves this.' In adopting this position, Magendie has hypostatized the law which the psychologists of the English school of associationism considered to be the fundamental law of mind.
4. Will is not an active agent or faculty. Rather, it is the perception of 'desire'. 'We give the name of will to that modification of the faculty of perception by which we experience desires.' Happiness or unhappiness depends on whether or not desires are satisfied. The derivative nature of the concept of will in the philosophy of Ideology is consistent with the passive sensationalism which had characterized this approach since Condillac.
It is characteristic of Magendie's separation of sensation and muscular motion from the analysis of the higher functions, that motor functions have no place in his exposition of the properties of the understanding which he was attempting to explain as functions of the brain. The action of the nervous system which produces muscular contractions is a phenomenon distinct from the will. 'Desires have been generally confounded with that cerebral action which presides over the
1 Magendie, 1843, p. 50. Cf. Broca's findings: below, Chapter 4.
2 Ibid., p. 50.
4 Ibid., p. 151. Once again, Magendie is less confident of the evidence for the role of the hemispheres than Flourens.
contraction of the voluntary muscles. I think it advantageous to the student that this distinction should be established. In another place, he says,
From these considerations, it may be inferred that the will and the action of the brain, which produce directly the contraction of the muscles, are two distinct phenomena. But the direct experiments of modern physiologists, and what has already been said respecting the influence of the cerebrum and cerebellum on the movements, have clearly established this truth. These experiments have clearly demonstrated that, in man and mammiferous animals, the will more particularly resides in the cerebral hemispheres. The direct cause of the movements appears, on the contrary, to have its seat in the medulla spinalis. If we separate the spinal marrow from the rest of the brain by an incision near the occiput, we prevent the will from determining and directing these motions, though they are, nevertheless, executed. As soon, however, as the separation takes place, they become irregular in extent, rapidity, duration, and direction.
Thus, Magendie concluded that will is a cerebral action which causes motion, but the production of the muscular contractions necessary to execute the motion is not cerebral but is instinctive and is associated with the following structures: spinal nerve roots, spinal cord, corpora quadrigemina, cerebral peduncles, thalamus, corpora striata, and cerebellum. The quality of his evidence is not always high, and some of his findings were not supported by later research, but the important point is clear. There was no role for the hemispheres in the direct production of muscular motion, just as there was none for any of the senses except sight. The sensory-motor analysis of the spinal cord and its partial extension to structures higher up the neuraxis was a distinct topic from the analysis of the phenomena of the understanding. It employed different methods and assumptions and was part of a separate intellectual discipline. In fact, except for the vague correlations between sensibility, memory, judgement, and desire with the activity of the cerebrum, Magendie had nothing original to say about the higher functions from either a physiological or psychological viewpoint. He was no more successful than Gall had been in relating his important new discoveries to the actual physiology of the brain, and his psychological conceptions were a reversion to the functions which Gall had attempted to replace with a naturalistic biological approach. Magendie's method and his work on the spinal cord provided the foundations of later important concepts and findings, but these could not be fully.
1 Magendie, 1843, p. 151.
2 Ibid., pp. 252-3.
3 Ibid., pp. 252, 243-6. Cf. Olmsted, 1944, pp. 125-6.
exploited until the hiatus which his own work exemplified was eliminated.
It would be artificial to propose a discussion of the relations between Magendie's work and phrenology. The only point to be made is that there was very little relation, except in the contrast between their methods, assumptions, and approach to the study of organisms. Magendie does mention Gall on anatomical topics several times. He notes that phrenologists were particularly concerned with the topic of instinct but 'with little appearance of success'. His only extended comment appears in a footnote, where he discusses cranioscopy and reveals that his passionate rejection of this aspect had prevented him from paying sufficient attention to Gall's work to understand or profit from his approach to the study of the functions of the brain.
Johannes Mueller's Handbüch
Johannes Peter Mueller was the third great exponent of the experimental method in this period. He received his doctorate at Bonn in the same year that Flourens and Magendie were publishing their most important findings (1822). He then moved to Berlin and was called to Rudolphi's Chair (1833) which thereby became the first chair of physiology in Germany. He is credited with introducing experimental physiology into that country. In the light of their similar roles in their respective countries, some interesting comparisons can be made between Magendie and Mueller. Magendie had begun his investigative career with a rejection of the counsel of despair of the vitalists in the name of the experimental method. Mueller had scornfully rejected
1 Magendie, 1843, pp. 143, 247.
2 Ibid., pp. 155-6
3 'Phrenology, a pseudo-science of the present day; like astrology, necromancy, and alchemy of former times, it pretends to localize in the brain the different kinds of memory. But its efforts are mere assertions, which will not bear examination for an instant. Craniologists, with Dr Gall at their head, go even farther, they aspire to nothing less than determining the intellectual capacities by the conformation of the crania, and particularly by the local projections which they remark. A great mathematician presents a particular elevation about the orbit; this is said to be the organ of calculation. A celebrated artist has a large bump on the forehead; that is the seat of his talent. But, replies some one, Have you examined many heads of men who have not these capacities? Are you sure that you do not meet with the same projections, the same bumps? That is of no consequence, replies the craniologist; if the bump is found, the talent exists, only it is not developed. But here is a great geometrician, or a great musician, who has not your bump. No matter, replies the sectary, you must believe. But, replies the skeptic, the aptitude should always exist, united with the conformation, otherwise it will be difficult to prove that it is not a mere coincidence, and that the talent of the man depends really on the particular form of his cranium. Still, replies the phrenologist, believe! And those who delight in the vague and the marvellous, do believe. There is some show of reason in this, for they thus amuse themselves, while the truth would only cause them ennui.' (Ibid., p. 150.)
the experimental method, especially the work of Flourens, in his early writings and had searched for 'divine life in nature'. He remained a thoroughgoing vitalist but embraced the experimental method after moving to Berlin. Thus, his writings contain precise findings, many of which remain valid, while their theoretical context is less appealing to the modern reader. Magendie eschewed such theoretical embroidery. On his empirical work. On the other hand, Magendie did his experiments in the context of medicine and with constant reference to its clinical applications, while Mueller's career marks the emancipation of physiological research from such practical demands and its establishment as an autonomous discipline.
Mueller's original work will be considered in the light of the influence his specific findings exerted on later workers. For the present it is important to stress the general influence of his major writing in physiology. Where Magendie had written an excellent textbook for students, Mueller provided the first exhaustive compendium since Haller's. His Handbüch der Physiologie des Menschen (1833-40) brought together all the notable results of physiological, anatomical, and psychological research and brought to bear on these the results of comparative anatomy, chemistry, and physics. It thus became the international authoritative source. It was translated into many languages and remained pre-eminent until the advent of Darwinism.
After writing the Handbüch Mueller turned to research in comparative anatomy, specializing in marine research. Nordenskiöld reports that he had a strong tendency to overwork and that he suffered from proud egoism, fits of melancholy, and hallucinations. He is believed to have ended his own life as his worries increased and his powers declined.
Mueller was extremely influential as a teacher. The list of justly famous pupils who worked under him has few parallels in the history of science: Schwann, Virchow, Henle, Remak, Kölliker, Du Bois-Reymond, and Helmholtz. It is apparent that Mueller's vitalism was not imparted to his students with the same success as was his methodology and technical expertise, since these men were the main instruments of the spread of somaticism and the experimental method in biology. Their applications of these approaches extended from work
1 Nordenskiöld, 1928, p. 384.
2 Murphy, revised ed., 1949, p. 92.
3 See below, Chapter 3.
4 Nordenskiöld, 1928, p. 384; Murphy, 1949, p. 96; Boring, 1950, pp. 33-5, 46; Singer, 3rd ed., 1959, p. 393.
5 Nordenskiöld, 1928, pp. 382-3.
6 Ibid., pp. 382, 388.
on cells and tissues to the consideration of physiology, optics, and the conservation of energy.
The three major exponents of the experimental method in neurophysiology had much in common in addition to their commitment to a method. Flourens, Magendie, and Mueller all contributed to the application of sensory-motor analysis to the functional organization of the nervous system. There were minor variations in how far up the neuraxis they applied it, but they all refrained from including the cortex in the direct initiation of muscular movements. They shared the view that the cerebrum was inexcitable. Their respective views on sensory functions defy neat summary, but they joined in rejecting cortical localization. They explicitly opposed Gall's concepts of function and his organology, though their reasons were diverse. Flourens' opposition was in the name of a Cartesian view of the unity and independence of the mind and a belief in free will, both of which he felt to be threatened by Gall's analyses and his tendency toward materialism. He was equally opposed to the sensationalism of Condillac and the Idéologues. Magendie, on the other hand, followed the Idéologues and was led from their philosophical position to his own experimental work. The result of this adherence was the exclusion of the study of the higher functions from what is usually seen as the domain of experimental physiology, and its discussion in terms of introspective and philosophical analysis.
Mueller rejects Gall's divisions and localizations of intellectual functions in favour of a single faculty of 'attention,’ and his views on the passions in favour of a single striving 'appetitus'. He does not claim that such localizations have been disproved, but he believes them to be unlikely, given his view of the functions themselves.
The conception of ideas, thought, and emotion, or the affections, are modes of consciousness. There is no sufficient reason for admitting the existence of special organs or regions set apart in the brain for the different acts of the mind, or for regarding these as distinct powers or functions. They are, in fact, as we shall presently show, merely different modes of action of the same power.
The other basis of his objection to phrenological faculties and organs is an associationist view of mentation.
1 Flourens, 1846, pp. 26-7.
2 See Temkin, 1946.
3 Mueller, 1842, p. 1345.
4 Ibid., pp. 1368-9.
5 Ibid., p. 1345.
It is true that the mind is rendered conscious of external impressions only through the medium of the nerves of sense, and their action on the brain: but the retention and reproduction of mental images of external objects of sense, exclude altogether the notion of particular orders of ideas being fixed in particular parts of the brain; for example in the ganglionic corpuscles of the grey substance. For the thoughts accumulated in the mind become associated in the most various manners, in a chronological succession, according to the relation of simultaneous occurrence, or according to their similarity or contrariety; and these relations of the ideas or thoughts to each other change every moment.[l]
From these diverse arguments a uniform result emerged: discussions of the higher functions have a vagueness that effectively precluded their experimental exploitation. The experimental techniques available at the time could only lead to equivocal results which allowed Mueller to conclude in favour of his own views. For example, he reports negative results from various experiments designed to elicit muscular contractions from irritation or injury of the hemispheres, corpora striata, optic thalami, and the corpus callosum. He also reports the ablation and stimulation experiments of Flourens and others in some detail. However, he does not feel compelled to adhere to Flourens' views of the functions of the hemispheres. He only reports the data and reaches the following weak conclusion, which he turns to his own purpose:
It is evident from these experiments, and from the effects of pressure on the cerebral hemispheres in man, that they are the seat of the mental functions; that in them the sensorial impressions are not merely perceived, but are converted into ideas; and that in them resides the power of directing the mind to particular sensorial impressions-the faculty of attention.
Beyond this he does not go, and his views would thus be irrelevant to the debate on cerebral localization if he did not follow this discussion with a firm rejection of Gall's psychology as well as his organology. Once again, vague findings, vaguely reported, allow him to draw the conclusion he pleases. He argues that there are 'no facts calculated in the slightest measure to prove the correctness of the hypothesis generally, or the correctness of the details of the doctrine founded upon it’.
1. Mueller, 1838. Cf. p. 837, where Mueller repeats Napoleon's comment that Gall's faculties are not fundamental but are merely conventional results of living in society. In rejecting this as a bad psychological foundation for concepts of function, Mueller reveals his inability to appreciate the fact that the relation of such faculties to living in society was precisely Gall's point in formulating a set of functions which were relevant to the life of organisms in their natural environments.
2 Ibid., p. 836. Cf. pp. 834-6.
3 Ibid., p. 837.
He rejects Gall's faculties, 'a part of which are totally unpsychological' and feels that 'we may at once exclude from the forum of scientific researches these arbitrary dogmas, which can never be proved'.
With regard to the principle, its possibility cannot, a priori, be denied; but experience shows that the system of organs proposed by Gall has no foundation, and the histories of injuries to the head are directly opposed to the existence of special regions of the brain destined for particular mental faculties. Not only may both the higher and lower intellectual faculties-as, reflection, imagination, fancy, and memory-be affected by lesion of any point on the surface of the hemispheres; but it has been frequently observed that different parts of the hemispheres can aid the action of other parts in the intellectual functions, and frequently where the removal of portions of the surface of the hemispheres has become necessary in the human subject, no change in their moral and intellectual powers has ensued. M. Magendie is very right in placing cranioscopy in the same category with astrology and alchemy.
The fact that Mueller rejected Gall's faculties and reverted to the philosophers' faculties of memory, imagination, and so on, is a regressive step from the point of view of a biological approach to psychology. However, for the moment, the main point is not the particular form which conceptions of the higher functions took. It is, rather, that the analysis of higher functions and their cerebral bases was neglected. It was making no progress, and attention was increasingly turned elsewhere.
The contrast between the vagueness with which higher functions were discussed and the new approach suggested by the Bell-Magendie law is striking. The study of sensory-motor functions was at once philosophically safe and precise. The result is that sensory-motor interpretations increasingly fill the conceptual void left by the muddled approach to higher functions. The contrast between Mueller's treatment of Gall and Flourens and his treatment of the Bell-Magendie law reflects this radical change of emphasis. He refers to the doctrine of the functional division of the spinal nerve roots as 'one of the most important truths of physiology'. He attributes the view, to Bell, and its partial experimental confirmation to Magendie. After reviewing the evidence, he retained doubts about how completely proved the theory was and conducted his own experiments on frogs. He concludes that 'The foregoing experiments leave no doubt as to the correctness of Sir C. Bell's theory'.
1 Mueller, 1838, p. 837.
2 Ibid., pp. 837-38. Cf. above, p. 88n.
3 Mueller, 1838, p. 642.
4 Ibid., pp. 640-6.
5 Ibid., p. 644.
In reviewing these developments over a century later, one can still feel some sense of the significance of this finding for students of the nervous system. When one encounters it after all the vague, confused, and contradictory results of previous investigators there is a quickening. At last! A clear, unambiguous, replicable experimental fact about the physiology of the nervous system: something on which to build. To the modern physiologist it may seem comically exaggerated that the functional division of the spinal roots was ranked second only to Harvey's discovery of the circulation of the blood. In its historical context, however, it is not difficult to share this evaluation. One of the disappointing facts about the scientific method as compared with speculation is that it permits the investigation of only those problems which are amenable to rigorous testing. In return for this emotional disappointment, science gives relative intellectual certainty. Consequently, some of the most important and elegant findings within science have not been very significant when considered in terms of their value to human life. Astronomy provides many notable examples. The excitement engendered by the Bell-Magendie law was because it was the first step in making an area of central interest to man amenable to scientific investigation. Since science advances only where its method allows, it is not surprising that the sensory-motor analysis of the nervous system came increasingly to replace the older systems of analysis which, though more subjectively appealing and relevant, were not amenable to experimental testing.
The functional division of nerves and physiological phenomena in terms of sensation and motion was obviously not a novelty in the nineteenth century. A cursory and unsystematic search for earlier uses finds that Aristotle gives it as a distinguishing criterion for animal life. It is as old as Greek medicine (Hippocrates), anatomy (Herophilus), and physiology (Erasistratus). It is fundamental to Galen's view of the nervous system, to Vesalius', and to many others'. In all these instances the sensory-motor view coexisted with some form of faculty psychology. The significance of the nineteenth-century analysis lay first in its experimental demonstration in the central nervous system and second in the progressive extension of the concept as the fundamental explanatory principle in both physiology and psychology.
What was required for the full exploitation of the Bell-Magendie law was a suitable theoretical context for bringing it into contact with
1 Singer, 1957, pp. 20, 28-32. Cf. Liddell, 1960, p. 48.
2 Riese, 1959, pp. 26-7.
3 Singer, 1952, pp. 2, 3, 39.
psychology. One aspect of this context had been available since Locke and Hartley in the psychology of sensation and association. It only remained to bring about the synthesis of the physiological with the psychological concepts of sensation in the first instance. Second, the sensationalist bias of the Lockean tradition had to be overcome by the provision of an adequate theory of muscular motion. The resulting balanced sensory-motor psycho-physiology could then, perhaps, transform the old epistemological psychology into a unified theory of knowing, feeling, and doing which, through its links with physiology, might constitute a natural science. These developments took over fifty years after the public statement of the Bell-Magendie law in 1822, and their story takes one back, in the first instance, to the association psychology itself. This tradition had to take on new interests which move it from preoccupation with the philosophical and introspective analysis of the subject-object relationship in knowing, to the psychological process of learning by doing. Finally, this change of approach had to be related to the nervous system in a new, evolutionary context.
The Association Psychology
In order to understand the union of the Bell-Magendie view of the nervous system with a psychology of sensation and motions, it is necessary to have some idea of the psychology of sensation and motion, it is necessary to have some idea of the psychological developments which occurred prior to the emergence of the unified view. This history is that of the Lockean tradition of associationist psychology. The major figures in the history of the association psychology are Hobbes, Locke, Hume, Hartley, Condillac, Thomas Brown, James Mill, J. S. Mill, Alexander Bain, Herbert Spencer, and G. H. Lewes. Bain and Spencer developed the sensory-motor psycho-physiology which was adopted by Hughlings Jackson and David Ferrier in their clinical and experimental studies of the nervous system. The following remarks are concerned with
1 The following exposition of the associationist psychology owes much more to its secondary sources than its primary ones. In every instance the primary sources have been consulted, but the order of study has been largely guided by histories and articles so that I can claim little originality for the result. My heaviest debts are to Warren, 1921, and J. S. Mill, new ed., 1867, but I have also consulted the following works: Aaron, 1955; Albee, reprinted, 1962; Baldwin, 1905, 1913; Boring, 1950; Brett, Ed. Peters, 1953; Cassirer, 1955; Dennis, 1948; Flugel 1951 ; Halévy, translated Morris, 1952; Hamlyn, 1961 ; James, 1890, 1892; Lange, 1925; Lewes, 1857; Mackintosh, 1860; Merz, 1896, 1903; Murphy, 1949; Pillsbury, 1929; Rand, 1912; Ribot, translated Fitzgerald, 1873; Robertson, 1875; Smith, new ed., 1962; Stephen, new ed., 1962; Stewart, 1860; Stout, 1898; Willey, new ed., 1962; Wolf, 1952. For the present I only want to mention the major figures and indicate that, as far as integration of associationism with empirically supported physiological concepts is concerned, no important contributions were made until the work of Alexander Bain.
associationism itself from the viewpoint of its eventual synthesis with experimental sensory-motor physiology and the concept of cerebral localization in the work of Ferrier.
The analysis of mind undertaken by the associationists grew naturally from their philosophical empiricism. Beginning with the sensationalism of Hobbes and explicitly formulated by Locke in opposition to a priori reasoning and the Cartesian doctrine of innate ideas, this a posteriors psychology sought to demonstrate that all knowledge and all experience could be accounted for by combinations of sensations and perceptions, caused in the first instance by external stimuli. True, Locke had postulated two sources of ideas-sensation and reflection. But the vagueness of his concept of reflection gradually led to the explanation of complex mental phenomena in terms of the relations among simple sensations, and the ideational complexes which they formed. The single explanatory principle which was eventually extended to account for all mental processes was the 'association of ideas'. Locke was not responsible for the systematic use of the principle of association. He only provided the phrase in a section added to the fourth edition of his Essay. 'At first a mere incident in the sensationist theory, it at length became the sole means of explaining all the great variety of experience that lies beyond sensation.[l] Thus, two principles defined the view: (1) the complex is formed from the simple by means of (2) the law of association. It can be seen immediately that associationism was to be the historical opponent of faculty psychology, and that its explanatory task was to reduce faculties to aggregates of elementary sensory units. The union of these basic units was accounted for in terms of mechanical connection, or a chemical analogy of compounding or fusion.
With the publication of David Hartley's Observations on Man-His Frame, His Duly, and His Expectations (1749), the association psychology first assumed a definite form and a psychological character not wholly derived from epistemological questions. Hartley was the first to apply the association principle as a fundamental and exhaustive explanation of all experience and activity. Hartley's interest in association was stimulated by an essay by a Reverend Mr Gay, who had written a dissertation in which he attempted to explain morality and all affections in terms of pleasure-pain and associations. Gay claimed to be a disciple of Locke, and has been credited with the first clear statement of
1 Warren, 1921, p. 155.
2 Mill, 1867, p. 107.
3 For a fuller treatment of Gay's theory and his reaction to explanations in terms of instincts and innate ideas, see below, p. 176.
utilitarianism, and the effective founding of the association psychology. Prior to this, the principle of association was applied only in the context of the phenomena of intellect and knowledge. Locke's sensationalism was an epistemological view in opposition to innate ideas as a source of knowledge. The principle of association was a relatively unimportant corollary of this position. Gay used Locke's general approach for very different purposes. He was concerned with primarily psychological issues: the origin of the moral sense and the passions. He also opposed innately given mental contents, but his opposition was to innate instincts. The principle of association became his central thesis for explaining the psychological experiences of the feelings of right and wrong, of love and hate, and of other passions. Gay and Hartley converted associationism from a view about the suffering of experience, whereby our ideas about the natural connections of things can be led astray by chance or custom, to a general psychological theory including affections and motions (both voluntary and involuntary). Associationism was not free from an epistemological bias after Gay and Hartley, but its centre of interest had shifted to the investigation of psychological processes. In concerning himself with the phenomena of motion, Hartley went beyond either Locke or Gay. Moreover, he joined his psychological theory with postulates about how the nervous system functions. His sensations were paralleled by vibrations (derived by analogy to Newtonian mechanics) of 'elemental' particles in the nerves and brain. Although he says that sensations are occasioned by the vibrations of small particles of the white medullary substance of the nerves, spinal cord, and brain, which are caused by the effects of external objects, he eschews consideration of causal relations among these and attempts to avoid the materialist (though not the fatalist) implications of his theory by means of a belief in psychophysical parallelism. Psychophysical parallelism remained characteristic of the association psychology up to and including its union with physiology in the formulations of Bain, Spencer, Jackson, and Ferrier.
The relations among sensations, ideas, and muscular motions as well as the faculties of memory, imagination, fancy, understanding, affection, and will are accounted for by Hartley in terms of repetitive
1 Halévy, 1952, p. 7; Albee, 1962, pp. 86, 90.
2 Hartley's interest in motion did not significantly influence the main line of the associationist tradition until the work of Bain, who drew his concept of activity from the German physiologist Johannes Mueller. This topic had been virtually ignored by the psychologists of association in the interim but had been kept alive in physiological writings. Mueller's theory was drawn from Erasmus Darwin and J. C. Reil, both of whom, in turn, had adopted it from Hartley. See below, Chapter 3, and Lewis, 1958, p. 160. See below pp. 114-21.
associations. In relating the phenomena of sensation, ideation, and motion to the nervous system he lays down the principles of physiological psychology which Ferrier would later combine with the concept of cerebral localization. Although Hartley did no experiments on the brain, his principles constituted the first physiological psychology of the associationist school. In fact, if one discounts Descartes' speculations in Traité de l'Homme (published posthumously in 1662), Hartley can lay claim to being the founder of the physiological psychology of higher functions.
The spectre of materialism raised by Hartley's view (in spite of his disclaimers) combined with the scepticism of Hume's philosophy to provoke a reaction in the Scottish 'common sense' philosophers, Reid and Stewart, who returned to a form of innate ideas in their faculty psychology. Their successor, Thomas Brown, attempted a reconciliation with associationism and drew heavily on Cabanis and de Tracy for his views on the role of the muscle sense and touch in revealing the external world. His posthumous Lectures on the Philosophy of the Human Mind (1820) is an eclectic work with elements of Reid, Stewart, and the French sensationalists. Its major contributions lie in his emphasis on the muscle sense (and thereby on the role of motion in sensation and learning) and his elaborations of the secondary laws of association. He follows Reid and Stewart in their reaction against Hartley and therefore rejects the physical aspect as materialistic, while employing the metaphor of 'mental physiology'. Brown's reintroduction of some associationist principles in his view of 'suggestion' and his recognition of the importance of physiology, even though he would not actually relate his views directly to the nervous system, were both indications of more explicit developments that were to follow.
James Mill's Analysis of the Phenomena of the Human Mind (1829), returns to the main line of the tradition of Locke and Hartley. He accepts Hartley's concept of mental phenomena rather than that of his teacher, Stewart, or Brown's intermediate position. He applies himself to extending and completing Hartley's doctrine. Hartley had been concerned to prove the validity of the associationist view. Mill assumed it, and later writers in the school could extend a doctrine which was taken as a settled starting point. All experiences, affections, and will are resolved into sensations and ideas. The elements of his analysis are the five
1 Hartley certainly deserves a more careful study than any which I have seen. The most useful recent source is Oldfield and Oldfield, 1951. For Hartley’s views on cerebral localization, see Hartley, 1749, I, 39, 40, 61, 63, 68, 73, 121, 162, 212, 272.
senses, the muscle sense, alimentary sensations, and the pleasure-pain principle. Since James Mill's associationism served as a foundation for later extensions of the doctrines of the school, it may serve as a yardstick for measuring later developments. First, its aims: the philosophic bias was still strong in his work. He saw the analysis of the mental powers as a necessary preliminary to a valid logic, a new (Utilitarian) morality, and sound pedagogical principles. He was not concerned with psychology for its own sake. The relevant context for Mill's psychology is his interest in legislation and teaching. His Utilitarian allegiances insured that his psychology would be concerned with a theory of action. However, these same interests effectively precluded any pursuit of comparative observations. As for relations with physiology, he went all the way back to Locke, whose position is quoted at the head of Mill's first chapter:
I shall not at present meddle with the physical consideration of the mind, or trouble myself to examine wherein its essence consists; or by what motions of our spirits, or alterations of our bodies, we come to have any Sensation by our organs, or any Ideas in our understandings; and whether those ideas do in their formation, any or all of them, depend on matter or no. These are speculations which, however curious and entertaining, I shall decline, as lying out of my way in the design I am now upon. Locke, i. I, 2.
The psychology of J. S. Mill is secondary to his logical and epistemological interests. What he has to say about psychology proper is included in his Logic (1843), his Examination of Sir William Hamilton’s Philosophy (1865), his notes to the edition of his father's Analysis which he edited with Bain and others (1869), and an article which he wrote on 'Bain's Psychology' (1859).
The last of these provides an excellent indication of J. S. Mill's views on the association psychology.
The great problem of this form of psychology is to ascertain not how far this law extends, for it extends to everything; ideas of sensation, intellectual ideas, emotions, desires, volitions, any or all of these may become connected by association under the two laws of Contiguity and Resemblance, and when so connected, acquire the power of calling up one another. Not, therefore, how far the law extends, is the problem, but how much of the apparent variety of the mental phenomena it is capable of explaining; what ultimate elements of the mind remain, when all are subtracted the formation of which can be in this way accounted for; and how, out of those elements,
1 See Halévy, 1952, pp. 455-78.
2 James Mill, 1829, I, 2.
the law, or rather laws, of association, the remainder of the mental phenomena are built up. On this part of the subject there are, as might be expected, many differences of doctrine; and the theory, like all theories of an uncompleted science, is in a state of progressive improvement. [l]
However, Mill does not himself contribute much to the development of the theory. For the execution of this task he defers extravagantly to Alexander Bain, who
has stepped beyond all his predecessors, and has produced an exposition : the mind, of the school of Locke and Hartley, equally remarkable in what it has successfully done, and in what it has wisely refrained from-an exposition which deserves to take rank as the foremost of its class, and as marking the most advanced point which the a posteriors psychology has reached.
In later editions of his Logic, Mill adds the following note to his discussion 'Of the Laws of Mind':
When this chapter was written, Professor Bain had not yet published even first part ('The Senses and the Intellect') of his profound Treatise on the Mind. In this the laws of association have been more comprehensively stated and more largely exemplified than by any previous writer; and the work, having been completed by the publication of 'The Emotions and the will', may now be referred to as incomparably the most complete analytical exposition of the mental phenomena, on the basis of a legitimate induction, which has yet been produced.
1 J. S. Mill, new ed., 1867, pp. 108-9.
2 Ibid., p.99
3 Mill, 8th ed., 1872, p. 557. Mill's faith in Bain's work had a more practical aspect. He persuaded his own publisher to print Bain's The Senses and the Intellect. It lost money, and when Bain was having difficulty getting the second volume published, Mill and Grote guaranteed the publisher against loss to the extent of £100. Thus, The Emotions and the Will appeared 1859, and Mill's review in the Edinburgh Review furthered its success. (Packe, 1954, p. 410.) Similar generosity was extended by Mill to Comte and to Spencer when their work was threatened by financial difficulties. (Ibid., pp. 282, 433-4.) Bain was still a student at Aberdeen when he first met his hero in 1842. Bain was twelve years younger than Mill, but he was immediately asked to read the proofs of Mill's Logic, for which he provided many valuable suggestions and examples. (Ibid., pp. 289, 271.) Bain walked home with Mill from India House every day during the next five summers and thereafter all year round until Mill married in 1851. (Ibid., pp. 291, 359.) Bain had started out as Mill's protégé but rapidly came his friend and colleague, and they maintained close relations until Mill's death in 1873. Bain assisted in major revisions of the third edition of the Logic and in preparing the 1869 edition of James Mill's Analysis. Bain also wrote a biography of James Mill and John Stuart Mill, a Criticism with Personal Reflections (1882). See also Mill, edited Elliot, 1910, and Mineka, 1963, for correspondence with Bain. The Mill-Bain letters have not been published or even located, and we have only the excerpts which Bain included in his biography of J S. Mill.
Bain's education in psychology was drawn from the standard works: Locke, Hume, Hartley, Reid, Stewart, Brown, James Mill, and J. S. Mill.  However, it will be seen that he shifted the whole direction of the association psychology.
1 J. S. Mill taught Bain personally and presented him with James Mill's Analysis as a gift (Bain, 1904, p. 112).
2 For further thoughts on the associationist tradition, see Young, 1966, pp. 20-4; Young, 1967a, pp. 123-4.
The Human Nature Review © Ian Pitchford and Robert M. Young - Last updated: 28 May, 2005 02:29 PM