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he extended the Bell-Magendie law a stage higher so that the thalamus was the highest sensory center and the corpus striatum the motor ganglion.54 From the physiological writings of Johannes Müller he adopted an emphasis on motion which was novel for the associationist tradition, whose stress on sensation had developed naturally from their interest in epistemology.55 This new emphasis provided psychology with a balanced sensory-motor view. Instead of concentrating on how we come to know through suffering experience, Bain inaugurated an interest in behavior which eventually became the dominant theme in behaviorist psychology — the concept of reinforcement.   
         In evaluating Bain's systematic treatises more broadly,56 one must conclude that associationism provided an inadequate explanation of the complex phenomena of emotion, instinct, and the biological functions which Gall had stressed.57 Also, while Bain attempted to correlate most of the functions of the brain with psychological processes, he left out the cortex and provided theories which had little contact with general biology.   
        Where Bain gave the association psychology a new emphasis on motion and a new alliance with physiology, Herbert Spencer provided it with a new foundation in evolutionary biology. Like Bain, Spencer derived his initial interest in psychology from phrenology and even wrote several phrenological articles and designed an instrument for measuring bumps.58 The psychological portions of his first book, Social Statics (1851), were based on a phrenological view of man and of adaptation.59 We are fortunate in having an essay written in his phrenological period and partially revised after he came under the influence of the associationists George Henry Lewes and John Stuart Mill.60 One can point with some confidence to the place in the text where his revision stopped, since the language shifts abruptly from associationist terms to phrenological faculties. 61
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54 Robert B. Todd and William Bowman, The Physiological Anatomy and Physiology of Man, 2 vols. (London: Parker, 1845), pp. 350-351; Bain, The Senses, pp. 40-47, 53, and 3rd ed. (1868), pp. 44-45.   
55 Müller, Elements of Physiology, Vol. I, p. 828; Vol. II, pp. 931-950; Bain, The Senses (1855), pp. v-vi, 289; (1868), pp. 59, 64-73, 290-91, 296-306; cf. Mill, Dissertations and Discussions, Vol. III, p. 121.   
56 Bain, The Senses (1855); The Emotions and the Will (London: Parker, 1859).   57 Bain's On the Study of Character was a failure. It went unnoticed by the critics and by Bain's contemporaries. There was no second edition. For criticisms of the adequacy of l9th-century associationism for explaining the phenomena of emotions and personality, see Mill, Dissertations and Discussions, Vol. III, p. 132; Ribot, English Psychology, p. 327; Gordon W. Allport, Personality. A Psychological Interpretation (New York: Holt, 1937), p. 87.   
58 Herbert Spencer, An Autobiography, 2 vols. (London: Williams & Norgate, 1904), Vol. I, pp. 200-203, 225, 227-228, 246-247, 297, 378-379, 540-543, The Life and Letters of Herbert Spencer, ed. David Duncan (London: Methuen, 1908), p. 40; George B. Denton, "Early Psychological Theories of Herbert Spencer," American Journal of Psychology 1921, 32: 5-15; Jefferson, Selected Papers pp. 35-44.   
59 Herbert Spencer, Social Statics (London: Chapman, 1851), pp. 5, 19-20, 32-38 75-89, 274, 280, 466.   
60 Herbert Spencer, "The Philosophy of Style," in Essays: Scientific, Political and Speculative, 3 vols. (London: Williams & Norgate, 1901), Vol. II, pp. 333-369- Spencer Autobiography, Vol. I, pp. 225, 405. On the influence of Lewes and Mill, see ibid., pp. 378-379, 391-392, Life and Letters, pp. 418, 544.   
61 The transition occurs in Essays, Vol. II, p. 360. The last sentence in associationist language refers to "mental energy" and "strain on the attention." The next sentence contains the first mention of "perceptive faculties." The MS in the British Museum appears to be a re-copy of the revised essay and neither confirms nor refutes my reading (MS, p. 113).

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        The development of Spencer's theory of evolution is a fascinating but complex story.62 It grew out of phrenology, the study of zoology, and a contrary acceptance of Lamarck derived from Lyell's supposed refutation of Lamarck in the Principles of Geology. Rather than consider his general doctrine here, attention will be confined to its original context in psychology, that is, evolutionary associationism. Spencer argued for the continuity of all mental phenomena beginning with the contractions of the sensitive polyp and extending to the forms of thought. He also links the organism to the environment; psychology thereby becomes a biological science, and mind becomes an instrument of adaptation. Learning, in this new context, is the continuous adjustment of inner relations in the mind to external relations in the environment. If one suspends judgment on Spencer's "Lamarckian" mechanism, the relationship between associationism and evolution by the inheritance of acquired characteristics becomes one of simple extension. Habits are built up by the repeated juxtaposition of ideas in experience, and they are then transmitted as modifications in the nervous system. The tabula rasa of the individual is replaced by that of the race. This view allows Spencer to argue that the emotions, instincts, and faculties can be accounted for as stable phenomena for the individual, though their genesis is still explained by the experience of the species.   
        It was on the basis of these beliefs that Spencer criticized Bain.63 Bain had attempted a natural history of the mind, but the "nature" he consulted was the contents of his own mind — by introspection.64 Spencer argued that Bain should have relied instead on comparative and developmental studies and thereby become a genuine naturalist.65 In insisting on this, Spencer challenged a fundamental assumption of those psychologists who believed that philosophical and introspective analysis provides sequences and categories which can serve as a natural classification of mental life — that what we can arrive at by examining our own adult minds accurately reflects the actual synthesis in evolution and in individual experience.66 Plausible verbal analyses are replaced by biological observation and (later) experiment. Having said this, however, Spencer (and those who followed) failed to grasp its implications for psychology: the search which Gall had attempted for a genuine naturalism in the categories of psychological analysis.   
        Horace W. Magoun has claimed that there can be no question of "the predominant influence of Spencer upon Hughlings Jackson and, through him, upon the formation of evolutionary concepts of the organization and function of the brain in Western neurological thought."67 For his own part, Jackson considered his theories to be merely applications of Spencer's evolutionary associationism to the nervous system in the light of clinical evidence.68 There were two other important influences on Jackson's thinking. The first was Bain, whose motor theory was used by Jackson for a motor theory of speech, thus replacing the faculty concept.69 The second was
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62 This paragraph is expanded, with detailed documentation, in my paper on "The Development of Herbert Spencer's Concept of Evolution," Actes du XIe Congrès International d'Histoire des Sciences (Warsaw: Ossolineum, 1967), Vol. II, pp. 273-278.   
63 Herbert Spencer "Bain on the Emotions and the Will" (1860), in Essays, Vol. I, pp. 241-264.   
64 Ibid., pp. 242, 244, 247, 257.
65 Ibid., pp. 249-252.   
66 Ibid., pp. 254-256.
67 Horace W. Magoun, "Darwin and Concepts of Brain Function," in J. F. Delafresnaye, ed., Brain Mechanisms and Learning (Oxford: Blackwell, 1961), p. 17.   
68 Selected Writings of John Hughlings Jackson, ed. James Taylor, 2 vols. (London: Hodder & Stoughton, 1931), Vol. I, pp. 147 n., 238n, 375; Vol. II, pp. 40n, 42, 45, 80n., 98, 346n., 395, 431-432.   
69 Ibid., Vol. I, pp. 167-68, 39, 50-51; Vol. II, pp. 123, 233-234.

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        The development of Spencer's theory of evolution is a fascinating but complex story.62 It grew out of phrenology, the study of zoology, and a contrary acceptance of Lamarck derived from Lyell's supposed refutation of Lamarck in the Principles of Geology. Rather than consider his general doctrine here, attention will be confined to its original context in psychology, that is, evolutionary associationism. Spencer argued for the continuity of all mental phenomena beginning with the contractions of the sensitive polyp and extending to the forms of thought. He also links the organism to the environment; psychology thereby becomes a biological science, and mind becomes an instrument of adaptation. Learning, in this new context, is the continuous adjustment of inner relations in the mind to external relations in the environment. If one suspends judgment on Spencer's "Lamarckian" mechanism, the relationship between associationism and evolution by the inheritance of acquired characteristics becomes one of simple extension. Habits are built up by the repeated juxtaposition of ideas in experience, and they are then transmitted as modifications in the nervous system. The tabula rasa of the individual is replaced by that of the race. This view allows Spencer to argue that the emotions, instincts, and faculties can be accounted for as stable phenomena for the individual, though their genesis is still explained by the experience of the species.   
        It was on the basis of these beliefs that Spencer criticized Bain.63 Bain had attempted a natural history of the mind, but the "nature" he consulted was the contents of his own mind — by introspection.64 Spencer argued that Bain should have relied instead on comparative and developmental studies and thereby become a genuine naturalist.65 In insisting on this, Spencer challenged a fundamental assumption of those psychologists who believed that philosophical and introspective analysis provides sequences and categories which can serve as a natural classification of mental life — that what we can arrive at by examining our own adult minds accurately reflects the actual synthesis in evolution and in individual experience.66 Plausible verbal analyses are replaced by biological observation and (later) experiment. Having said this, however, Spencer (and those who followed) failed to grasp its implications for psychology: the search which Gall had attempted for a genuine naturalism in the categories of psychological analysis.   
        Horace W. Magoun has claimed that there can be no question of "the predominant influence of Spencer upon Hughlings Jackson and, through him, upon the formation of evolutionary concepts of the organization and function of the brain in Western neurological thought."67 For his own part, Jackson considered his theories to be merely applications of Spencer's evolutionary associationism to the nervous system in the light of clinical evidence.68 There were two other important influences on Jackson's thinking. The first was Bain, whose motor theory was used by Jackson for a motor theory of speech, thus replacing the faculty concept.69 The second was
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62 This paragraph is expanded, with detailed documentation, in my paper on "The Development of Herbert Spencer's Concept of Evolution," Actes du XIe Congrès International d'Histoire des Sciences (Warsaw: Ossolineum, 1967), Vol. II, pp. 273-278.   
63 Herbert Spencer "Bain on the Emotions and the Will" (1860), in Essays, Vol. I, pp. 241-264.   
64 Ibid., pp. 242, 244, 247, 257.
65 Ibid., pp. 249-252.   
66 Ibid., pp. 254-256.
67 Horace W. Magoun, "Darwin and Concepts of Brain Function," in J. F. Delafresnaye, ed., Brain Mechanisms and Learning (Oxford: Blackwell, 1961), p. 17.   
68 Selected Writings of John Hughlings Jackson, ed. James Taylor, 2 vols. (London: Hodder & Stoughton, 1931), Vol. I, pp. 147 n., 238n, 375; Vol. II, pp. 40n, 42, 45, 80n., 98, 346n., 395, 431-432.   
69 Ibid., Vol. I, pp. 167-68, 39, 50-51; Vol. II, pp. 123, 233-234.

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an unfairly neglected figure — Thomas Laycock.70 Just before Spencer worked out his theories on the basis of evolution, Laycock (who also had heavy debts to phrenology) applied the principle of continuity to all of the nervous system (including the cortex) on the basis of the older philosophy of biology, the great chain of being.71 Jackson's intellectual mentors provided him with the best of the old and the new versions of the principle of continuity as applied to the nervous system.
        Four aspects of Jackson's thinking are important in this context. First, on the basis of the views of Spencer and Laycock, Jackson held that the interpretation of the central nervous system in terms of sensation and motion (which began with the Bell-Magendie law) had to extend throughout the nervous system. As he put it in 1870, "If the doctrine of evolution be true, all nervous centres must be of a sensori-motor constitution."72 Since the highest centers have the same composition as the lower, being made up of cells and fibres, "It would be marvellous if, at a certain level, whether we call it one of evolution or not, there were a sudden change to centres of a different kind of constitution. Is it not enough difference that the highest centres of the nervous system are greatly more complicated than the lower?"73 Second, Jackson adopted Spencer's concept of cerebral localization — the only specific feature which Spencer retained from his earlier phrenological period.74 Centers of co-ordination for complex sensations and motions were localized in place of Gall's faculties. Complex mental phenomena were thus reduced to aggregates of sensations and motions paralleled by sets of fibres and cells.75 Third, Jackson explicitly applied this view to the cerebral cortex as a motor organ and argued against those who "think the cerebrum to be likened to an instrumentalist, and the motor centres to an instrument; one part . . . for ideas, and the other for movements."76 Even though some of his writings before 1870 are equivocal about the role of the cortex in movements,77 he did put the issue more clearly than anyone else and ridiculed those who "speak as if at some place in the higher parts of the nervous system we abruptly cease to have to do with impressions and movements, and begin all at once to have to do with mental states"78 — the view that "physical states in lower centres fine away into psychical states in higher centres."79
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70 Ibid., Vol. 1, pp. ix, 37, 123, 167.   
71 Thomas Laycock, ~Treatise on the Nervous Diseases of Women (London: Longmans, 1840); "On the Reflex Functions of the Brain," Brit. For. Med. Rev., 1845, 19: 298-311; "Phrenology," in The Encyclopaedia Britannica (8th ed., Edinburgh: Black, 1859), Vol. XVII, pp. 560-561; James Crichton Browne, The Doctor Remembers (London: Duckworth, 1938), pp. 40-41; Young, "Scholarship," pp. 25-26.   
72 Jackson, Selected Writings, Vol. II, p. 63.   
73 Ibid.   
74 Ibid., pp. 216, 234.   
75 Herbert Spencer, The Principles of Psychology (London: Longmans, 1855), pp. 606 611.   
76 Jackson, Selected Writings, Vol. I, p. 26n. After Jackson's ideas had received experimental support, he never tired of quoting this note in his later papers, e.g., ibid., pp. 42, 58; Vol. II, pp. 63-64, 67.
77 In fact, a close study of his writings before 1870 — when his view was demonstrated experimentally — shows that he was less emphatic than has sometimes been supposed in applying the hypothesis that the cortex was a motor organ: the corpus striatum held his loyalties as the primary motor organ in spite of striking evidence implicating the cortex in disorders of movement. Ibid., Vol. I, pp. 27, 38; Vol. II, pp. 121, 122-123, 127, 216, 233, 239, 240-241, 244. In 1868 he reported a case of ”corpus striatum Epilepsy" which involved a post-mortem finding of blood, the bulk of which "lay in one spot over the frontal convolutions, and was so placed as I imagined, to squeeze the corpus striatum...." The discussion refers all symptoms to the corpus striatum and does not mention the convolutions (ibid., Vol. II, p. 218; cf. Vol. 1, p. 9).   
78 Ibid., Vol. I, p. 48.
79 Ibid., Vol. II, p. 156.

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        This point was linked closely in Jackson's mind with a fourth — philosophical — issue. While his predecessors had indulged in two sorts of interactionism between the unitary mind and the unitary cortex on the one hand and between the mind and its sensory-motor instruments on the other, Jackson (again drawing heavily on Spencer) argued that a clear-cut dualism should be maintained without interaction and that one should postulate a doctrine of concomitance or psychophysical parallelism. The nervous system was to be uniformly sensory-motor, and its physiological processes were paralleled by ideas of sensation and movement.80 This assumption — in the hands of Freud (who adopted it from Jackson)81 and of the majority of later psychologists — continued to be used as a justification for ontological agnosticism about body and mind, while they and the physiologists pursued separate studies, seeking only occasional specification of what is happening in the world of matter and motion when something else occurs in the world of mind. Expressions of dualism could no longer find a convenient demarcation within the nervous system. The "organ of mind" could not be held to be physically as well as functionally discontinuous from the rest of the neuraxis. The fundamental separation of mind from body could still be expressed in the form of psychophysical parallelism, but there was continuity of structure, function, and analytic units within the nervous system itself.
        Meanwhile, there were two findings which led the sensory-motor school to consider cerebral localization with renewed seriousness. (The term findings is used advisedly, since the interpretations put on them were vehemently rejected by Jackson and Ferrier.)
        Paul Broca provided the first convincing evidence for cerebral localization in 1861. His work was an application of Gall's localizations. Indeed, the faculty of articulate language had been Gall's first discovery (the large flaring eyes which, Gall said, "gave the first impulse to my researches, and was the occasion of all my discoveries").82 However, Broca also insisted on precise study of the brain itself rather than reliance on the measurement of cranial protuberances.83 Broca also argued that speech was an intellectual faculty, not a motor function.84 As he said in a significant aside, "Everyone knows that the cerebral convolutions are not motor organs."85 Even though his first case showed partial paralysis, Broca referred this symptom to the corpus striatum, though the patient's speech defect was localized in the third frontal convolution of the cortex.86
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80 Ibid., Vol. I, pp. 49, 52, 52 n., 55; Vol. II, pp. 84-86, 156.   
81 Sigmund Freud, On Aphasia. A Critical Study (1891), trans. E. Stengel (New York: International Universities Press, 1953), pp. 54-56. This position was held consistently throughout Freud's writings, up to and including his last book, An Outline of Psychoanalysis (1940), trans. J. Strachey (New York: Norton, 1949), pp. 13, 34. See also E. Stengel, "A Re-evaluation of Freud's Book On Aphasia: Its Significance for Psycho-analysis," International Journal of Psycho-analysis, 1954, 38: 85-89; Walther Riese, "Freudian Concepts of Brain Function and Brain Disease," Journal of Nervous and Mental Disease, 1958, 127: 287-307.   
82 Gall, On the Functions of the Brain, Vol. V, p. 8. The best treatment of the history of research on aphasia in the l9th century remains Henry Head, Aphasia and Kindred Disorders of Speech, 2 vols. (Cambridge: Cambridge Univ. Press, 1926), Vol. I, Chs. 1-5.
83 Paul Broca, "Remarks on the Seat of the Faculty of Articulate Language" (1861), trans. Gerhard von Bonin, Some Papers on the Cerebral Cortex (Springfield: Thomas 1960), pp. 58-59, 72.   
84 Ibid., pp. 54, 57
85 Ibid., p. 70.
86 Ibid. Broca's researches on the seat of the faculty of articulate language once again roused the Cartesians, who maintained that the brain must act as a whole. The positions in this debate were paralleled by political views: the conservatives were Cartesians, while the younger liberals and republicans favored cerebral localization. The debate was acrimonious and prolonged in Parisian medical circles. See Head, Aphasia, Vol. I, p. 25.

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        Nine years later two young German physicians, Gustav Fritsch and Eduard Hitzig, published a paper entitled "On the Electrical Excitability of the Cerebrum," which demonstrated by experiment that electrical stimulation of discrete cortical areas produced combined muscular contractions.87 Until this epoch-making result, no new experiments fundamentally affecting the role which the cortex was supposed to play in movement had been conducted for almost fifty years. Thus, it is appropriate that Fritsch and Hitzig address their remarks directly to Flourens.88 In the intervening period the sensory-motor paradigm had been applied to progressively higher structures in the nervous system, until a point had been reached just below the cortex (thalamus and corpus striatum). This analysis was not extended by further experiments for twenty-five years. Fritsch and Hitzig eliminated this hiatus. They established cortical excitability, a role for the cortex in the mechanism of movements, and the doctrine of cerebral localization. From their experiments on dogs, five centers were specified at constant foci: for the muscles of the neck, for the extensors and adductors of the anterior leg, (behind that) for the flexion and rotation of the same leg, for the posterior leg, and for the facial nerve.89 Fritsch and Hitzig stress an important reason for the delay in discovering the electrical excitability of the cerebral cortex. The assumption of cerebral equipotentiality had allowed experimenters to refrain from examining and stimulating every part separately.90 Thus, Flourens' belief in Cartesian dualism and the indivisibility of the mind appears to have made it easy for him to refrain from the sort of systematic, localized ablations which would have confirmed cerebral localization. Fritsch and Hitzig were also Cartesian dualists and wrote in interactionist terms about the soul and its material instruments. Their results supported cerebral localization of motor functions, but they argued that their findings left room for other (nonmotor) parts of the cortex as the organ of mind. They felt that psychological functions might also be localized.91 Their views should be contrasted with those of the sensory-motor school in two respects: (1) their interactionism and (2) their distinction between psychological functions and sensory-motor functions.
        The examples of Flourens and of Fritsch and Hitzig indicate that philosophical assumptions can, and do, strongly influence the conduct of research and the interpretation of results, even though no empirical finding can falsify a philosophical belief. The relations between philosophical assumptions and scientific research form one of the most interesting aspects of the study of the history and philosophy of science, but it is important to appreciate that these interactions do not occur as formal deductions: the relationships are more subtle and idiosyncratic.
        Where Fritsch and Hitzig had found five motor centers, an Englishman, David Ferrier, soon found fifteen and went on to specify areas for each of the five senses.92 Ferrier began his experiments as an attempt to confirm Jackson's clinical findings by reproducing seizures by means of electrical stimulation of the cortex.93  He also
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87 Von Bonin, Some Papers,  pp. 81, 96.
88 Ibid., pp. 75-78.
89 Ibid., pp. 83-84.
90 Ibid., p. 90.
91 Ibid., pp. 77, 92, 96.
92 David Ferrier, "Experimental Researches in Cerebral Physiology and Pathology," West Riding Lunatic Asylum Medical Reports, 1873, 3: 30-96; The Functions of the Brain (London: Smith, Elder, 1876), pp. 163-196; 2nd ed. (1886), pp. 268-345. [I visited this mental hospital in August 1996. It was, like most of the old custodial asylums, closed, but on the map of the site, one ward was named ‘Ferrier’.]  
93 Ferrier, "Experimental Researches," pp. 30, 85-87; The Localization of Cerebral Disease (London: Smith, Elder, 1878), p. 14.

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set out to confirm and extend the work of Fritsch and Hitzig.94 The significance and continuity of influences can be seen from the fact that the monograph which summarized and interpreted his findings was dedicated by Ferrier to Jackson.95 In fact, he is as lavishly deferential toward Jackson as Jackson was toward Spencer.96 Sherrington, in turn, dedicated his classical lectures on The Integrative Action of the Nervous System (1906) to Ferrier.97 In his obituary notice of Ferrier for the Royal Society Sherrington pointed out that Ferrier had done the most important research in proving cerebral localization, in placing it at the center of neurological interest, and in providing the basis for a "scientific phrenology."98
        The significance of Ferrier's work was quickly appreciated. Accounts from the British Association, the President's Address to the Royal Society, and the 1901 supplement to the Encyclopaedia Britannica, as well as contemporary reviews of his works, all confirm that it made as much a stir as the Bell-Magendie law had fifty years earlier.99 Even Carpenter was moved to rank Ferrier's localizations among the greatest advances in the physiology of the nervous system which had been made in the last fifty years, and he acknowledged the existence of the missing fibres connecting the cortex and lower centers, although he held fast to his former separation of the cortex and its functions from the sensory-motor paradigm — the hiatus which was undermined in the very report which he was praising so lavishly. He saw no inconsistency between his former views and Ferrier's findings.100
        Ferrier referred to the psychological interpretation of his findings as "scientific phrenology." He reasoned as follows. His first experiment was on a guinea pig which died before its responsiveness to electrical stimulation could be determined. His next experiments were on rabbits and cats. Electrical stimulation produced more or less localized convulsions (thus confirming Jackson) but no discrete movements.101 It was in his fourth experiment (on a cat) that Ferrier obtained localized, discrete movements. For example, in one place stimulation produced slow
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94 Ferrier, "Experimental Researches," p. 30.
95 "To Dr Hughlings Jackson who from a clinical and pathological standpoint anticipated many of the more important results of recent experimental investigation into the functions of the cerebral hemispheres, this work is dedicated as a mark of the author's esteem and admiration." Ferrier, The Functions of the Brain  (1876), p. v.
96 David Ferrier, "The Localisation of Function in the Brain" (MS). Communicated by J. B. Sanderson 5 March 1874. Archives of the Royal Society AP.56.2. (Abstract in Proceedings of the Royal Society, 1874, 22: 229-232), MS, p. 129V; cf. Ferrier, The Functions of the Brain (1876), pp. 256-257; Localization, p. 14.
97 Charles S. Sherrington (New York: Scribner's, 1906), p. v: "In token recognition of his many services to the experimental physiology of the nervous system."
98 Charles S. Sherrington, "Sir David Ferrier, 1843-1928 " Proc. Roy. Soc., 1928, 103B:  viii-xvi, pp, x, xiii.
99 William Rutherford, "Address to the Department of Anatomy and Physiology," Report of the Forty-Third Meeting of the British Association for the Advancement of Science (London: Murray, 1874), Transactions, pp. 119-123, p. 122; George B. Airy, "President's Address," Proc. Roy. Soc., 1873 1874, 22: 2-12, p. 9; Anon. (C. S. Sherrington), "Phrenology," in The New Volumes of the Encyclopaedia Britannica  (10th ed., Edinburgh: Black, 1902), Vol. XXXI, p. 710 George C. Robertson, "Critical Notice of 'The Functions of the Brain', by David Ferrier," Mind, 1877, 2: 92-98, p. 92. For an accurate dramatization of the significance of Ferrier's findings, see Jürgen Thorwald, The Triumph of Surgery, trans. R. and C. Winston (London: Thames & Hudson, 1960), Ch. 1. The medical applications of Ferrier's findings in localizing neurosurgery deserve further historical study.   
100 William Carpenter, "On the Physiological Import of Dr. Ferrier's Experimental Investigations into the Functions of the Brain," West Riding Lunatic Asylum Med. Reps., 1874, 4: 1-23, pp. 2, 7-8, 18-19; Mental Physiology, pp. 709, 715, 719.   
101 Ferrier, "Experimental Researches," pp. 34 38.

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flexion of the phalanges of the left forepaw and elevation of the left shoulder; in another place it produced signs of pain, screams, and kicking with both hindlegs, especially the left.l02 Thus, he found that motion and signs of sensation resulted from stimulation of the cortex. However, he soon extended his interpretations. In a later experiment (on a dog) stimulation produced behavior interpreted as dream like on general observation, including wagging of the tail and spasmodic twitching of the right ear.l03 Ferrier received a grant from the Royal Society which allowed him to extend his researches to monkeys. He identified centers for advance of the opposite hind limb, as in walking; and retraction, with adduction of the opposite arm, as in swimming.104 By 1874 he was convinced that he was investigating not merely artefacts and induced contractions, but the basis of voluntary movements.l05 Thus, his inferences moved from contraction to purposive movement to biological functions. This reasoning led him to claim that he could "artificially excite conditions similar to normal psychic or volitional stimuli" and to "translate into their psychological signification and localize phrenologically the organic centers for various mental endowments.''106
        The resulting conception of the functions of the brain is a corollary of the theories of Bain, Spencer, and Jackson, for which Ferrier felt that he provided the experimental evidence: ". . . it must follow from the experimental data that mental operations in the last analysis must be merely the subjective side of sensory and motor substrata" — a view which he attributes to Jackson.l07 He adds in the second edition, "For the cerebral hemispheres consist only of centers related respectively to the sensory and motor tracts, which connect them with the periphery and with each other.''l08 Ideas are revived associations of sensations and movements, thought is internal speech, and intellectual attention is ideal vision.l09 The centers for special sensory and motor activities "in their respective cohesions, actions, and interactions form the substrata of mental operations in all their aspects and all their range.''110 In short, all conceptions of function are reducible to sensation, motion, and association. Ferrier's work represents the final extension of the Bell-Magendie paradigm to the most rostral part of the neuraxis — the cerebral cortex — and its use as an all-embracing explanatory conception in both physiology and psychology.
        When Gall finished his work On the Functions of the Brain in 1825, he re marked that he would have liked to withhold it longer but that death was imminent, "and I must be content with leaving this first effort in the physiology of the brain, far less perfect than it will be fifty years hence.''111 In 1876 Ferrier's monograph, with the same title, appeared. In comparing them, one finds the balance between physiological and psychological statements reversed. Gall's work was almost wholly devoted to the discovery and exposition of the faculties or functions. Ferrier devotes only ten per cent of his text to what he calls "the subjective aspect of the functions of the brain." Most of his book is devoted to the "physiological aspects," and he concluded that these consist of "a system of sensory and motor centers. In their subjective aspect the functions of the brain are synonymous with mental operations, the consideration of which belongs to the science of psychology." All that
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102 Ibid., pp. 41-42.
103 Ibid., p. 51.
104 Ferrier, The Functions of the Brain (1876), pp. 141-142.
105 Ferrier, "Localisation" (MS), pp. 95 97, 117-118.
106 Ferrier, "Experimental Researches," pp. 72, 76.
107 Ferrier, The Functions of the Brain
(1876), pp. 256-257.
108 Ibid. (1886), p. 426
109 Ibid., pp. 437, 462, 463-464.
110 Ibid., p. 467.
111 Gall, On the Functions of the Brain Vol. VI, p. 293.

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Ferrier felt was needed to convert his physiological findings into psychologically significant statements was the assumption of psychophysical parallelism and the phrase "subjective aspect.''112   
        If Gall was naive in believing that the organization and physiology of the brain corresponded with his faculties in a one-to-one fashion, Ferrier was equally so in suggesting that the primary sensory and motor areas could explain psychological functions in a simple manner. He had localized sensory and motor areas, but he had not provided a psychophysiology which accounts for the adaptations of organisms to their environments. As a recent commentator put it, "Whatever its role in the production of muscular activity, the motor cortex cannot be regarded as the seat of any function recognisable to the student of behaviour.''113
        Experimental sensory-motor physiology was on a firm experimental basis, built up by progressive extension of the Bell-Magendie law — a certain fact about the nervous system — and then united with the concept of cerebral localization. However, cerebral localization had become scientific only by abandoning the goals which Gall had laid down at the beginning of his research: to relate the significant variables in the character and behavior of men and animals to the functioning of the brain. The sensory-motor school was undoubtedly right in rejecting Gall's faculty psychology. However, in being grounded on a secure physiological basis, the sensory-motor tradition cut itself off from the approach to psychology which was the most important aspect of Gall's work and which had been extended by Spencer's conception of psychology as a biological science. In rejecting Gall's answers, it lost sight of the significance of his questions. Insufficient attention was paid to what the sensory-motor elements should be required to explain. In default of significant questions, the only answers that were forthcoming were about sensory modalities and muscular movements and led only to a partial understanding of the primary projection areas of the somatic cortex. The role of many of these in normal behavior has yet to be determined. Questions about adaptive, biologically significant functions had to be asked anew by other branches of biology which developed independently on the basis of other aspects of the ideas of Bain, Spencer, and Darwin. The problem which Ferrier bequeathed to the present century was that of retaining scientific rigor while regaining contact with biologically significant functions.
   Gall and Ferrier can be seen as extremes on a continuum of possible approaches in brain and behavior research. Gall stressed functions as adaptive and related them to character, mastery of the environment, and social and intellectual achievements. He allowed his catalogue of functions to dictate how the brain must be organized and made no significant findings in neurophysiology. Ferrier, on the other hand, sacrificed the significance of functions to physiological accuracy. As John Dewey said in 1900, "Unless our laboratory results are to give us artificialities mere scientific curiosities, they must be subjected to interpretation by gradual re-approximation to the conditions of life.''114 That is, mediation between the extremes required integration of the independent findings of physiologists, psychologists, and students of animal behavior (ethologists). Though Gall was unable to follow his own advice, latter-day behavioral scientists are in a better position to do so. He said, "Whoever would not remain in complete ignorance of the resources which
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112 Ferrier, The Functions of the Brain (1876), pp. 255-257.
113 O. L. Zangwill, "The Cerebral Localisation of Psychological Functions," Advancement of Science 1963-1964 20: 335-344 p 337
114 John Dewey, "Psychology and Social  Practice," Psych. Rev., 1900, 7: 105-124, p. 119.

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cause him to act . . ., should know, that it is indispensable, that the study of the organization of the brain should march side by side with that of its functions.''115   
        Before concluding, one might recall Gall's influence and suggest that there is still more to be learned from him. As G. H. Lewes said, "Gall rescued the problem of mental functions from Metaphysics and made it one of Biology.''116 "In his vision of Psychology as a branch of Biology, subject therefore to all biological laws, and to be pursued by biological methods, he may be said to have given the science its basis.''117 His influence on Bain and Spencer was most significant, and lesser figures such as Laycock and Carpenter also derived much from Gall's approach. However, neither they nor their modern heirs — the behaviorists — have transcended the categories which Gall opposed in the name of biology. The functional psychology of William James and John Dewey advocated the study of mental functions as adaptations, but they also failed to provide new and significant categories.
        In 1940, Sherrington pointed out that the new phrenology was as far as the old had been from understanding the role of the nervous system in integrated behavior and that there were not even names for the categories which are ultimately needed.118 Modern brain and behavior research is still attempting to find ways of asking and answering the question, What are the functions of the brain? It appears that the answers to this question will, in the first instance, owe more to the field studies of the ethologist than to physiological experiments. It was Gall who made the point that we must first know the functions before we can ask intelligent questions about the organization and physiology of the brain. A century and a half later, one finds a recent reviewer of the concept of cerebral localization turning to Gall in support of the thesis that "in exploring the functions of the brain, I am convinced that we must limit ourselves to the study of biologically significant behavior patterns, no matter how complex their underlying physiology may be.''119 This, it seems to me, is the scientific lesson of the foregoing account.   
        Turning to the philosophical issues, if anyone believes that the problems set by Descartes no longer plague biological psychology, he should consider the fact that modern research is not dealing only with the two languages of extended substances and thinking substances. Though Descartes might well recognize the activities and concepts of the physiologist, he would be puzzled by the coexistence of the categories of function in the Passions of the Soul and the Treatise on Man (that is, memory, reason, intelligence) with the atomistic units of the association psychology. These last have in turn been made objective in a third language—the stimuli and responses of the behaviorist which, their claims not withstanding, have defied reduction to matter and motion. Thus, we have one language of brain, two of mind, and a fourth of behavior. Add to these the concepts of the evolutionary biologist, and we find five sets of variables.
        The problem for the future can be approached by two paths. The first involves transcending these several languages with a new ontology. The second — which is at present in vogue — is to find translation rules among them. Whichever approach is taken, it seems clear that careful historical studies can help to provide the per
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115 Gall, On the Functions of the Brain, Vol. II, pp. 45-46   
116 George H. Lewes, The History of Philosophy from Thales to Comte, 2 vols. (3rd  .ed. London: Longmans, 1867-1871), Vol. II, p. 425
117 Ibid., p. 423.
118 C, S. Sherrington, Man on His Nature (Cambridge: Cambridge Univ. Press, 1940), p. 228
119 Zangwill, "Cerebral Localisation," p. 338.