A text-book of mental diseases

Front matter

WOM ILL i

22900234003 me

PRESENTED

Preface

A KNOWLEDGE of mental diseases is obligatory upon students who wish to graduate in medicine, and it is obviously necessary for those who intend to become medical officers of asylums ; it is, moreover, a weapon of offence against the accused in courts of justice, and a weapon of defence against the prosecutors. All those who either fight in the ranks of alienists, or make professional skirmishes on their flanks, without the advantage of a special vocation, require to know the true position of psychiatry, and especially its useful applications, its ascertained facts, and its practical rules, shorn of redundancies and parade. They are professional and amateur alienists who need to have set before them, not a disjointed encyclopedia of mental disturbances, pathological rarities, biographical lists, historical accounts, psychological curiosities and anatomical freaks, but an organized, simple and truthful collection of clinical pictures that are clearly distinguished one from the other, which have the reason for their existence in a distinction deeper than that of mere outward appearance, and which therefore lead those who are acquainted with them to a scientific procedure in their management and treatment of the insane.

There is, however, another class of inquirers to whom psychiatry affords a speculative position, sometimes the only one available, from which they can view still more profound questions. Those who are interested in psychiatry as their vocation, among whom are included many asylum physicians, lawyers, writers, and politicians, do not ask for instruction in the practical methods of dealing with the insane, but seek the solution of deeper problems that perplex the human mind, of a biological, anthropological, psychological, ethical, and philosophical nature. Psychiatry, which as a practical speciality is so humble, becomes, notwithstanding its actual deficiencies, one of the most aristocratic of sciences on account of the position it occupies as a branch of biology. It is the advanced sentinel of biology in the speculative field, and although its arms are short, its vision is far-reaching. Although there are many things that it cannot see, yet the horizons to which it stretches are vast, theideals . at which it aims are high, and its points of contact with other sciences are verynumerous. The views upon questions of anatomy, evil vili PREFACE cytology, physiology, psychology, pathology, and sociology, that the science of mental diseases is constrained to advance, to analyse, and to discuss in the neighbouring fields of knowledge, in order to enrich its own, are very numerous and varied, and among the most important with which it has to deal ; and perhaps the day will come when psychiatry will project upon these sister sciences, in still stronger rays, the light it has received from them.

In this book I have endeavoured to reflect in due proportions, and without emphasizing their antagonisms, the two tendencies that underlie modern psychiatry, the Martha and Mary into which they divide, inspiring on the one hand practical measures, and on the other the attainment of ideals. The practical man wants to know what psychiatry is ; the idealist strives to ascertain what it will become. The one requires facts, and only those that are certain, harmonious, and of genuine practical utility ; the other is interested in hypotheses, in the direction that is being taken by an advancing science, in its past, and in its future. As Richet has remarked, however, modern critics are induigent to the man who collects facts uncritically, and unconsciously alters, exaggerates, and invents them, whilst they are implacable to him who guesses at truth, and naturally leaves his hypotheses undemonstrated, however rational, useful, and probable they may be. Tyros in criticism, who adopt positivism to the letter, many of these aristarchs of the Universities are led, without knowing . it, to believe all statements to be true and all hypotheses false. There are, however, alleged facts that are illusory and hypotheses that become verified. It would be better if there were more rigour in the examination of facts and less precipitation in the condemnation of hypotheses.

In the chapters upon general psychopathology I have not avoided new and old details of anatomy and physiology, the claims of psychology, the inductions of pathological anatomy, and the exposition of conjectures already known, but still discussed, regarding the mechanism of thought, which form the cope-stone of the fundamental principles of biology. In regard to these matters it is necessary, however, to adopt liberal views. In the chapters in which special psychopathology is dealt with I have, on the contrary, preferred the guidance of experience, and have avoided all doctrinal systems.. Heredity, degeneration, the biological factors in the causation of insanity, and the laws of association, cannot supersede clinical science, which is based mainly on the direct observation of the most common and evident facts. Psychiatry ought boldly to spread its wings when it flies in the domains of the general sciences with its wealth of principles and hopes, but it should avoid dispersion of its forces and use every precaution when it walks in the field of applied clinical science.

Chapter I The Seat Of The Psychical Processes

HisrorIcAL NOTE - : - : THE PRESENT PosITION oF THE PROBLEM The Data of Physiology and paperoni. Anatomy The Data of Embryology The Data of Human Pathology The Data of Normal Anatomy - THE Positive EVIDENCE OF THE EXISTENCE OF cera. Privo

Chapter II The Causes Of Mental Diseases External Causes

Somatic Causes

Psychical Causes

Social Causes - “ = : a a

INTERNAL CAUSES

Diathesis A

Psychical Degeneration

Heredity - -

Chapter III The Anatomical Substratum Of Mental Diseases

I. MACROSCOPICAL APPEARANCES OF THE LESIONS OF THE CEREBRAL

CoRTEX - - 1. Terminal Results of Early Morbid Pitcano 2. Focal and Diffuse Lesions in the Adult -

II. ELEMENTARY LESIONS OF THE CEREBRAL CORTEX AND ITS ANNEXES -

1. Lesions of the Nerve Cells (a) Acute Processes - (b) Subacute Processes (c) Chronic Processes 2. Lesions of the Nerve Fibres 3. Lesions of the Neuroglia - 4. Lesions of the Vessels and of the Mata III. ExTRACORTICAL AND ExTRACEREBRAL MoRBID CHANGES ix

Xx CONTENTS

CHAPTER IV Tur GENERAL PHYSIOLOGY OF THE SENSORIAL AND SENSORY PRO

CESSES - THE PATHOLOGY OF SENSIBILITY - Coenesthesis

Tactile Sensibility, Tusio: Sensibility, Sensibility to Pan

The Genetic Sense

Taste and Smell

Hearing and Sight : Hallucinations and Illusions” - - Mechanism of Hallucinations Applications of the Theory

Hallucinations due to Irritative Stimuli that act directly on the

Brain - 5 E Hallucinations occurring I the Eyes are Closed Repetition of Thought - : - - Figured Hallucinations 5 Combined Hallucinations

Hallucinations that present Therdeleees in the Hiosni of Dreams

Hallucinations of Peripheral Origin - - Unilateral Hallucinations of Hearing

Illusions - : - : - Conclusion :

Pseudo-Hallucinations or torcia Hallaninaticne

Chapter V | Ideation

THE PsycHOLOGY oF IDEATION - PATHOLOGY OF IDEATION - - - - RAPIDITY oF THOUGHT : - PREVALENT IDEAS - : - - OBSESSIVE IDEAS - - - .

DELUSIONAL CONVICTIONS AND VERSO DOUBTS THE QUANTITY OF THE IDEAS - = ALTERATIONS IN THE ARRANGEMENT OF THE IDEAS STATES OF SEMICONSCIOUSNESS - - -

Chapter VI

THE PHYSIOLOGY OF MEMORY : - THE PaTtHoLOGYy or MEMORY Agenesia of the Mnemonic Impressions The Obliteration of Mnemonic Imprints Disorders of Mnemonic Evocation - Irregularities in the Act of Mnemonic Ravvanition

PAGE

132 134

135 136 138 138 140

172 179 179 180 184 190

CONTENTS

Chapter VII The Sentiments

THE PHYSIOLOGY OF THE SENTIMENTS THE PATHOLOGY OF THE SENTIMENTS - : - 1. Pathological Variations of Mood Sentimental Depression Sentimental Exaltation Sentimental Indifference - 2. Pathological Variations in the Shhets of the Pinphiins

3. Pathological Variations of the re and of the Habitual

Character - - -

Chapter VIII Movements And Other External Reactions

THE PsycHoLoGy oF MovEMENTS - THE PATHOLOGY OF CENTRIFUGAL INNERVATION - 1. The Conduct Anomalies of the Will Anomalies of the Instincts (1) Conservation of the Individual (2) Conservation of the Species 2. Motor Expression, Speech, and Writing Anomalies of Expressive Movement Anomalies of Speech x Acquired Defects of AcHchlation Congenital Defects of Articulation Forms of Dysphrasia - Anomalies of Writing - 3. The Common Reflexes Visceral Reflexes - Tendon Reflexes - Reflexes of the Pupils

CHAPTER X PELLAGRA ETtIOLOGY - = 2 2

THE MORPHOLOGICAL AND TO RI or MAIZE AFFECTED BY

MouLD K A Si x " ‘ x PATHOGENESIS 7 J 2 È 2 È xi

PAGE

270 273 281

288 290 xii CONTENTS

SYMPTOMS - - - - PATHOLOGICAL ANATOMY - Cerebro-spinal Axis Visceral Lesions DEMOGRAPHICAL DATA PROPHYLAXIS AND TREATMENT

MyYXx@DEMA OF ADULTS ENDEMIC CRETINISM Symptoms Pathological nue Etiology : Pathogenesis - - - Prophylaxis and io :

PAGE

293 300 300 302 303 306

344 352 355 358 359

CONTENTS

Pathological Anatomy - : - - x A

Chapter XIV Progressive Paralysis

SYMPTOMATOLOGY - : - - Signs and Course of ine Uomo RO Mental States and Delusions Crises and Seizures Motor Symptoms Disturbances of Sensation Visceral and Trophic Disturbances Clinical Varieties of Progressive Paralysis CoURSE - : - ETIOLOGY - - “ PATHOGENESIS x : - : - : PATHOLOGICAL ANATOMY - : Macroscopical Lesions affecting the fai : - - Microscopical Lesions affecting the Nervous System Changes in the Spinal Cord and Peripheral Nerves Changes external to the Nervous System DIFFERENTIAL DIAGNOSIS TREATMENT

Chapter XV Infantile Cerebropathies (acquired Idiocy) Etiology - - : : : A ; È Pathological Anatomy

SYMPTOMS AND CLINICAL FoRMS ~ Psychical Changes - È - È 2 E Motor Changes - - - È - , ; > Hemiplegia - : È "a : : Diplegias - = a = Cerebral miao common to the Hemiplegic and Diplegi Forms - - Sensory Chanecs TREATMENT

Chapter XVI The Cerebropathies Of Adults

‘SENILE DEMENTIA - - : E Demential Symptoms - : 3 ‘Amential Symptoms - - È 7 Focal Symptoms - - È :

xiil

466 469 469

CLINICAL VARIETIES OF SENILE DEMENTIA - : - Course - . - - - Differential neuen - Pathological ea Pathogenesis Treatment

CEREBRAL HAMORRHAGE, RR AND ITRROO IE - .

CEREBRAL SYPHILIS CEREBRAL TUMOURS SCLEROSE EN PLAQUE HEAD TRAUMATISMS

Chapter XVII The Affective Psychoses

MELANCHOLIA - - = x 3 5 è Symptoms : - _ 3 : È Sense of Mental Pain - 2 5 i ‘ Delusions . = È a Abulia and Dono - - 2 : Other Symptoms - - È { s Course and Clinical Varieties - È : 3 3 Differential Diagnosis - - - . È Treatment x x 2 2 2 è MANIA - Sic : Symptoms x - - 5 x J è Course and Varieties’ - = è . 3 x . Differential Diagnosis - : - x PERIODIC MELANCHOLIA - - 3 PeRIODIC MANIA CIRCULAR INSANITY -

Chapter XVIII Neurasthenia

SYMPTOMS - : : Lassitude Paresthesias - : = : é Localized Pains Objective Symptoms = : General State - : : -

PsYCHICAL SYMPTOMS : - - - a é Agoraphobia - : . : È È Misophobia or Rupophobia - 7 o : Pathophobia Dysmorphophobia Fear of Responsibility - | : : Ereutophobia - è È x Obsession of ‘ How ?°° ah i Why ?” -

. Obsessive Ideas of Action

. 485 .

486 486 489 493 495 495

CONTENTS

DIFFERENTIAL DIAGNOSIS - — x È a 2

ETIOLOGY AND PATHOGENESIS - 3 -

TREATMENT x E È CHAPTER XIX HYSTERIA SYMPTOMS”) - - - pin ETIOLOGY AND COURSE TREATMENT - CHAPTER XX EPILEPSY SYMPTOMS” - : > A 4

The Epileptic Fit

Partial Fits

Epileptic Equivalents

Pre-epileptic and Post-epileptic Rats

Permanent Psychopathic States

Somatic Characters and Symptoms DIFFERENTIAL DIAGNOSIS. - - ETIOLOGY AND PATHOGENESIS - CLINICAL FoRMS AND COURSE OF THE DISEASE PATHOLOGICAL ANATOMY - - - TREATMENT -

CHAPTER XXI DEMENTIA PRACOX SYMPTOMS”) - = 4 o CoURSE AND CLINICAL VARIETIES - È

CausES AND NATURE OF DEMENTIA PRACOX TREATMENT - - . -

CHAPTER XXII

SEXUAL INVERSION (URANISM) È - - -

FETICHISM - -

CHAPTER XXIII

THE ETHICAL CRITERION IN DIAGNOSIS” - a“ 5

EVOLUTION OF THE NOSOLOGICAL CONCEPTION” - CLINICAL MANIFESTATIONS x - TREATMENT OF THE IMMORAL È = È

XV

566 588 593

597 597 600 601 606

608 609 611 620 621 625

633 652 663 666 |

673 676

CHAPTER XXIV PARANOIA

CLINICAL MANIFESTATIONS OF PARANOIA - - Delusion of Persecution > È - Ambitious Delusion : - Religious Delusion Erotic Delusion Querelant Delusion Impersonal Delusions Neologisms Hallucinations - Behaviour of Paranoiacs

TREATMENT OF PARANOIA

CHAPTER XXV IMBECILITY

CLINICAL MANIFESTATIONS -

Appearance of Imbeciles - - : -

Anatomical Stigmata of Degeneration -

Perception : -

Affectivity

intelligence

Movements -

Pronunciation, lan Language, and Writing - - CLINICAL VARIETIES - - -

CHAPTER XXVI ASYLUMS

FURTHER DEVELOPMENT OF ASYLUMS - --- OBSTACLES TO THE REGULAR HOSPITAL Tani OF NA DISEASES - Legal Restrictions : - - - False Interpretation of Staino Insidious Substitutes — - - PRACTICAL ARRANGEMENT Observation Hospitals - - Separation of the Aged and the one Agricultural Colonies - - : -

A TEXT-BOOK OF MENTAL DISEASES

CHAPTER I THE SEAT OF THE PSYCHICAL PROCESSES Historical Note

PSYCHIATRY consists, as yet, chiefly in a description of symptoms, Beneath an evident wealth of clinical phenomena it conceals gaps and uncertainties that leave its most essential problems unsolved.

It must not be forgotten that the study of mental diseases began to assume some degree of continuity only towards the end of the eighteenth century. Up to this time religious and philosophical prejudices, whilst they allowed the search (attended with but little success) for the seat of the soul in the body, had repressed every other tendency that seemed opposed to spiritualism. Consequently, the life of psychiatry, save for the luminous intervals of the Greek and Latin civilizations, was simply a prolonged lethargy, devoid of new acquirements, and without even the memory of those that had previously been made.

The awakening that occurred in the eighteenth century was due only in small part to scientific causes. It was a keener social sensibility rather than the ripening of medical opinion that | enforced the establishment of asylums, and so created the alienists. It created them before the revival of psychiatry had actually taken place, that they might set themselves to the arduous task of bringing about such a revival. It was only natural that their premature studies should result in a psychiatry that was purely descriptive. The whole attention of these eager but imperfectly equipped observers was absorbed by the external manifestations of mental disease that abound in the speech and conduct of the insane, and these, being easy to understand even without the assistance of special knowledge, readily produced the illusion of a rich and co-ordinated science where there was really only a lengthy enumeration of superficial phenomena.

Left to their own resources, and without the guidance of modern collateral knowledge, asylum physicians were led to abuse this facility of observation, and to multiply unduly the varieties of mental disease. There came to be a perfect kaleidoscope of psychoses and terminology, accepted by some, rejected and disputed by others, and destined to appear and disappear, or to change places, in the course of the fruitless succession of classifications and of schools. ig

A knowledge of symptoms, no matter how wide it may be, is sterile, apart from the study of pathogenesis. That a trauma, a poison, an infection, or a violent emotion, is capable of producing insanity, and of producing only certain forms of it, is recognized by the general public, as well as in psychiatry. The true problem does not consist in the identification of the causes of insanity, but in the analysis of the manner in which these causes operate on the cerebral organization. |

In a case in which a painful emotion that ought to have been of a passing nature is succeeded by a condition of chronic depression, with typical features of melancholia, we can trace a causal relationship, which on first view seems extremely simple, for both phenomena are of a psychical nature, and in no way very different, excepting in duration. Yet between these two subjective phenomena, the physiological mental pain and the melancholic depression, there is interposed a third term of a different order that cannot be disregarded—namely, a pathological process taking place in the brain. How is it that out of the emotional experience there can be materialized an organic change ? And how does this material reaction to an emotional stimulus, in its turn, become the source of subjective manifestations, such as those that constitute the various distressing feelings of the melancholic ? We may have a fair knowledge of the symptoms and the remote causes of mental diseases, but the intermediate processes, which are the immediate effect of the operation of the pathogenic agents and, at the same time, the immediate occasion of the psychopathic symptoms, almost always remain obscure. It is true that, in regard to some forms of insanity, we know that there is a constant connection between a certain morbid agent and a definite pathological change, but even in these cases we are ignorant of how the anatomical conditions produce the symptomatic picture. In order to be able to comprehend how these heterogeneous phenomena are linked together, it would be necessary to understand—in some measure, at least—how mental operations normally take place in the various regions and structural elements of the brain.

The same degree of obscurity does not obtain in the pathology of other organs. In many instances, indeed, the relation between structure and function is so clear that from the slightest functional disorder, such as a cardiac murmur, we can directly infer the material lesion that has produced it. This is frequently the case, not only in diseases of the heart, but also in those of other organs -—as, for example, the kidneys and eyes. The functions of these | organs are simple in comparison with those of the brain—so simple, indeed, that we may, with sufficient accuracy, compare the heart to a pump, the kidney to a filter, and the eye to a system of lenses. The biological significance of the brain does not permit of being adequately expressed in such ready formule. The brain distinguishes, beholds, hears, smells, tastes, touches, examines, excites, innervates, inhibits, speaks, writes, remembers, thinks, imagines, and reasons ; it hesitates and wills ; it suffers and rejoices. If we wished to sum up its activities in one or more metaphors, we should have to say that it is at once an observatory, an archive, a tribunal, and a government ; and there would still remain unnamed. other essential offices that cannot be expressed figuratively. Between what the brain really is and what it seems to be, between the indisputable complexity of its functions and the deceptive homogeneity of its structure, there is an abyss that is difficult in the extreme to bridge.

For these reasons, not only the lacune that still exist in cerebral physiology, but also the errors of the past, which in our scientific discussions we sometimes recall with an air of derision, deserve our kindly consideration and respectful indulgence.

To discover the seat of the soul in one or other of the viscera, or in the body as a whole, or in a single part of the brain, has been the great aim—indeed, almost the historical obsession— of those who have studied psychology from ancient until recent times. The certainty that the organ in question is the whole cerebral cortex was only reached within the last forty years. The credit of this discovery cannot be given to the alienists (Broca was an anthropologist, and Hitzig began his studies as a physiologist) ; but at the same time we cannot justly charge them with undue hesitancy. The problem is one that really goes beyond the limits of psychiatry, and extends into the domain of general biology. ) ut

So long as the arteries were regarded as channels filled with air, and the nerves were not distinguished from tendons, it was hardly irrational that the seat of the intellectual activity should by preference be sought for in the heart. This organ, being the anatomical centre of the arteries, connected with the lungs and with the peripheral sensory organs, and visibly under the influence of the passions, could very appropriately be looked upon as the viscus most evidently designed to be the place of interchange of the imponderable fluids, sound, ‘light, heat, sensations, thoughts, and affections, for the transmission, for- 1—2 mation, and transformation of which there appeared to be required at least a medium of air, if not one absolutely immaterial.

When, therefore, the ancients spoke of the soul and endeavoured to assign for it a residence outside the brain, they did not, like the modern exponents of cerebral localization, have in view a special nidus of thought, but rather a centre of life in general. It was likewise only in this sense that naturalists, less inclined than most others to metaphysical explanations, ventured to assign a soul to plants. The soul had thus extremely varied anatomical localizations. The theories elaborated regarding this question are a pa:t of history, and are capable of being grouped into categories more or less sharply marked off into epochs, schools, and tendencies.

1. Extracerebral Localizations, without any Participation of the Brain.

The theories composing this group are the most ancient. The early Greek philosophers were hylozoists. Losing sight of the subjective aspect of thought, they confounded not only thought with life, but also life with movement, and ended by believing that intelligence, like movement, is a universal property of matter. On the other hand, confronted by a precise problem of human physiology, they had, at least for a time, the good sense to put hylozoism aside. They did not endeavour to find intelligence elsewhere than in themselves. Unfortunately, they allowed themselves to be influenced by the preconception that the seat of intelligence must be an extremely active organ, and they therefore discarded the brain and devoted their speculations to the heart, blood, lungs, liver, and spleen. Each of these organs, either on account of its central position, its wide diffusion in the body, the prominence of its functional variations, or its size and apparent high temperature, appeared to be the seat of physical and chemical changes of a much more important kind than those that could be thought to take place in the cold and immobile mass of the brain, which current belief regarded as a gland that subserved the function of secreting the nasal mucus.

2. Mixed Localizations in Various Organs, including the Brain.

Theories of this nature flourished with Greek philosophy. The human mind was regarded from various points of view, according as it was concerned with the sensations, the passions, reason, bodily growth, etc. Each of these forms of mind was given a different residence. The most common classification was tripartite, and the highest office was almost always assigned to the heart.

The brain, although it could not but be allowed to take part in the division, was given a somewhat secondary office. Aristotle held that it served to cool the blood, and that it therefore had a sort of antagonism to the heart. When the heart prevailed, vitality and thought were at their height ; when the brain prevailed, vitality was lowered, the body became cooler, and thought was dulled. It was under the influence of this negative view that Aristotle, after having determined experimentally its insensibility to mechanical irritation, was led to maintain that the brain must be the organ of sleep.

At the beginning of the nineteenth century Bichat still held, as Plato had done, that the heart, and not the brain, was the seat of the affections. The definite transference to the brain of all the mental functions, including the affections, is somewhat recent. It was the meritorious achievement of Gall, who, notwithstanding the extravagant nature of his phrenology, succeeded in avoiding another error—namely, that of attributing to the affections a different localization (save within the limits of the cerebral cortex) from that of sensation and representation.

3. Localization in the Whole Body.

This theory of a diffuse and homogeneous localization, according to which there are not several psychical centres, but an absolutely decentralized psychical function, has both an ancient and modern origin and form.

Most of the scholastics, convinced that an imperceptible and perhaps indivisible functional action, such as that of thought, could neither be concentrated in a single organ nor shared by a few favoured and arbitrarily selected ones, adopted the maxim of Augustin: Anima in toto corpore tota et in omnibus eius partibus tota. This polypsychism of the scholastics is a first return step towards the Greek hylozoism, or towards panpsychism, which, in its strict meaning, excludes any serious attempt at anatomical localization.

By another path, not a few of the Darwinian evolutionists of the present day reach a panpsychism of a still more complete and unreserved nature. They trace back from the brain to the nervous system, from the nervous system to the corresponding primitive elements in ontogenesis, and from the organic world to the inorganic, through the ramifications of phylogenesis, and finally discover human intelligence in the chemical atom. These extreme evolutionists do not perceive that they abuse the law of continuity. According to their view, glimmerings of psychical functional activity exist in every part of the living organism ; and, if so, why not also outside it ? Haeckel, indeed, in his “ Perigenesis of the Plastidules,’” without denying the pre-eminence of the brain as the evolved organ of intelligence, regards even chemical affinity as an expression of will, or as a psychical phenomenon. If this view were correct, it would, a fortiori, be necessary to recognize a rudimentary intelligence i in all organized . beings, including even unicellular organisms. Thus the ancient roîs of Plato and Aristotle reappears, in modern dress, as the mind and motive force of the universe. But an intellect external to living and recognized organisms possesses no clear significance. This hypothetical force, the existence of which is improbable, and the idea of which only too evidently has its origin in the animism of savage and primitive peoples, helps in no way to explain that intelligence which we feel in ourselves, and which operates in beings similar to ourselves.

Recent researches upon chemotropism encouraged for a orale the tendency to panpsychism. Since chemotactic movements are useful to the beings which manifest them, and since all living things seem to be endowed with chemotactic properties, it was concluded that intelligence, or at least consciousness, is a universal attribute of organized matter, and that it existed before the brain.

Fortunately, Verworn and all the more authoritative investigators of chemotropic movements very soon arrived at an opposite conclusion. It would appear that these movements are not the ‘primary expression of intelligence, but a physiological and apsychical property of living things, which is merely included in the more complex mechanism of mental action. Thus, instead of employing intelligence to explain chemotropism, we can use chemotropism to explain many physiological phenomena, including—at least, in part and in their objective manifestations— those of intelligence, which perhaps result from a great complex of chemotropical actions, favoured by anatomical conditions of an altogether exceptional nature. These anatomical conditions are not completely fulfilled, except in the brain ; the ganglionic automatism of invertebrates, like the chemotropism of unicellular organisms, resembles and A intelligence, but it is not actually intelligence.

The tradition of diffuse localization, nea! however, to the whole central nervous system, still persists with some biologists— as, for example, Pfliiger, who holds that there is a spinal consciousness, on the ground that he has observed purposive and complicated movements on the part of the decapitated frog. It is preserved by all those—and they are numerous—who assign intelligence to invertebrates. According to Forel and Bechterew, the whole nervous system, including the sympathetic, was originally endowed with psychical functions ; but in consequence of the gradual centralization (ontogenetic and phylogenetic) of these functions in the cerebral cortex, the lower nervous organs were slowly deprived of them, whilst they continued to evolve in the direction of automatism.

4. Intracerebral Localizations of Centralized Type.

The concentration of the mental functions in one limited, definite, and single organ of the encephalon, or sensorium commune, in which the nerves would meet and the mental forces mingle, was the vain dream of the most illustrious anatomists and the most positive intellects of the eighteenth and nineteenth centuries. This organ, the existence and functional dignity of which was assumed in advance, and which was deemed to realize in its anatomical unity the assumed unity of the mind, was sought for everywhere, excepting in the open field of the cortex—as, for example, in the pineal gland (Descartes), in the caudate nuclei (Vieussens), in the corpus callosum (Willis), in the bulb (Rolando), in the cerebro-spinal fluid (SOmmering), or in a geometrical point (Kant). |

In order to attain his purpose of confining the intelligence to one organ, Descartes became an anatomist, and made a large number of autopsies. Outside the limits of his thesis he made a contribution of definite facts to our knowledge of the anatomy of the brain. Willis based his contentions upon anatomy, a science the progress of which he had advanced. Rolando went still farther, carrying out experiments upon animals. Sdémmering pointed to the arrangement of the cranial nerves, and argued that their activity always began and terminated in the walls of the ventricles, and that they were thus able to influence each other through the medium of the endocranial fluid. Lastly, Kant did not reach his conclusion by simple metaphysical deduction ; he examined the various attempts to arrive at an anatomical localization, and refuted them by weighty arguments.

5. Cortical Localizations.

That the intelligence should not at first be sought for in the cerebral cortex was but natural. The macroscopical distinction of this portion of the encephalon from the rest is not very evident, and, as regards the knowledge of its microscopical structure, it is sufficient to recall the fact that the nerve cells were discovered by Purkinje only in 1840. There was no ground for supposing that the cerebral cortex is so richly provided with cell elements. Nevertheless, Gall, with clear and gifted intuition, when studying the course of the cerebral nerves (1799-1820), noted the homology of the cortex with the nervous ganglia, and observed that, of all the parts of the brain, the cortex attains the largest proportions in man and in the most intelligent of the other vertebrates. The intellectual function of the cortex was fully demonstrated experimentally by Flourens in 1842, when he showed that the partial or complete destruction of the brain in lower animals is always followed by more or less marked loss of intelligence.