The Physical Basis Of Mind - free ebook by George Henry Lewes

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The Physical Basis Of Mind

George Henry Lewes

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THE PHYSICAL BASIS OF MIND.

THE PHYSICAL BASIS OF MIND.

With Illustrations. BEING THE SECOND SERIES OF PROBLEMS OF LIFE AND MIND. BY GEORGE HENRY LEWES. BOSTON AND NEW YORK: HOUGHTON, MIFFLIN AND COMPANY. The Riverside Press, Cambridge. 1891. AUTHOR’S EDITION. From Advance Sheets. The Riverside Press, Cambridge, Mass., U. S. A. Printed by H. O. Houghton &amp; Company....

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PREFACE.

PREFACE.

The title indicates that this volume is restricted to the group of material conditions which constitute the organism in relation to the physical world—a group which furnishes the data for one half of the psychologist’s quest; the other half being furnished by historical and social conditions. The Human Mind, so far as it is accessible to scientific inquiry, has a twofold root, man being not only an animal organism but an unit in the social organism; and hence the complete theory of its functions

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PROBLEM I. THE NATURE OF LIFE.

PROBLEM I. THE NATURE OF LIFE.

“La Physiologie a pour but d’exposer les phénomènes de la vie humaine et les conditions d’où ils dépendant. Pour y arriver d’une manière sûre, il faut nécessairement avant tout déterminer quels sont les phénomènes qu’on désigne sous le nom de vie en général. C’est pourquoi la première chose à faire est d’étudier les propriétés générales du corps qu’on appelle organiques ou vivans.”— Tiedemann , Traité de Physiologie de l’Homme , I. 2. “Some weak and inexperienced persons vainly seek by dialectic

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THE NATURE OF LIFE.

THE NATURE OF LIFE.

1. Although for convenience we use the terms Life and Mind as representing distinct orders of phenomena, the one objective and the other subjective, and although for centuries they have designated distinct entities, or forces having different substrata, we may now consider it sufficiently acknowledged among scientific thinkers that every problem of Mind is necessarily a problem of Life, referring to one special group of vital activities. It is enough that Mind is never manifested except in a liv

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THE POSITION OF BIOLOGY.

THE POSITION OF BIOLOGY.

3. Science is the systematic classification of Experience. It postulates unity of Existence with great varieties in the Modes of Existence; assuming that there is one Matter everywhere the same, under great diversities in the complications of its elements. The distinction of Modes is not less indispensable than the identification of the elements. These Modes range themselves under three supreme heads: Force, Life, Mind. Under the first, range the general properties exhibited by all substances; u

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ORGANISMS.

ORGANISMS.

8. It will be needful to fix with precision the terms, Organism, Life, Property, and Function. An organism, although usually signifying a more or less complex unity of organs, because the structures which first attracted scientific attention were all thus markedly distinguished from inorganic bodies, has by the gradual extensions of research been necessarily generalized, till it now stands for any organized substance capable of independent vitality: in other words, any substance having the speci

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VITAL FORCE.

VITAL FORCE.

14. A similar ambiguity to that of the phrase “ordinary matter” lies in the equally common phrase “Vital Force,” which is used to designate a special group of agencies, and is then made to designate an agent which has no kinship with the general group; that is to say, instead of being employed in its real signification—that which alone represents our knowledge—as the abstract statical expression of the complex conditions necessary to the manifestation of vital phenomena, or as the abstract dynam

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VITAL FORCE CONTROLLING PHYSICAL AND CHEMICAL FORCES.

VITAL FORCE CONTROLLING PHYSICAL AND CHEMICAL FORCES.

16. The facts relied on by the vitalists are facts which every organicist will emphasize, though he will interpret them differently. When, for example, it is said that “Life resists the effect of mechanical friction,” and the proof adduced is the fact that the friction which will thin and wear away a dead body is actually the cause of the thickening of a living—the skin of a laborer’s hand being thickened by his labor; the explanation is not that Life, an extra-organic agent, “resists mechanical

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CHAPTER II. DEFINITIONS OF LIFE.

CHAPTER II. DEFINITIONS OF LIFE.

25. Biology, the science of Life, being thus assigned its place in the hierarchy of objective laws, we now proceed to consider what the term Life symbolizes. By a large preliminary simplification, Life may be defined as the mode of existence of an organism in relation to its medium . To render this of any value, however, a clear conception of the organism is first indispensable; and this must be preceded by an examination of the various attempts to define life in anticipation of such a clear con

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ORGANISM AND MEDIUM.

ORGANISM AND MEDIUM.

53. But we have only one half of the great problem of life, when we have the organism; and it is to this half that the chief researches have been devoted, the other falling into neglect. What is that other? The Medium in which the organism lives. Every individual object, organic or inorganic, is the product of two factors:—first, the relation of its constituent molecules to each other; secondly, the relation of its substance to all surrounding objects. Its properties, as an object or an organism

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THE HYPOTHESIS OF GERMINAL MATTER.

THE HYPOTHESIS OF GERMINAL MATTER.

67. It may help to elucidate certain important points if I here examine the hypothesis which Dr. Beale has worked out with such patient skill, but with what seem to me such unphysiological results. He deserves, I think, more applause than has been awarded to him, not only for the admirable patience with which he has pursued the idea, but also for the striking definiteness of the idea itself—always a great advantage in an hypothesis, since it gives precision to research. If biologists have paid b

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ORGANISMS AND MACHINES;

ORGANISMS AND MACHINES;

and while on the one hand the legitimate striving of the biologist to display the mechanism of organic actions has been denounced by a certain school as Materialism and a hateful attempt to “rob Life of its mystery,” there has been on the other hand a misconception of this mechanism, as if its dependent actions were of the nature of machines, that is to say, as if organized mechanisms were strictly comparable with machines constructed of inorganic parts. No doubt the laws of Mechanics are the sa

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DOES THE FUNCTION DETERMINE THE ORGAN?

DOES THE FUNCTION DETERMINE THE ORGAN?

88. Closely connected with this law, which simply formulates the self-evident principle that every action is rigorously determined by the nature of the agent, and the conditions under which the act takes place , is the surprising question whether functions are dependent upon organs, or organs dependent on functions?—a question which sometimes takes this shape: Is Life the result of organization, or is organization the result of Life? The vitalist, who holds that Life is an extra-organic agent, i

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NATURAL SELECTION AND ORGANIC AFFINITY.

NATURAL SELECTION AND ORGANIC AFFINITY.

118. It is impossible to treat of Evolution without taking notice of that luminous hypothesis by which Mr. Darwin has revolutionized Zoölogy. There are two points needful to be clearly apprehended before the question is entered upon. The first point relates to the lax use of the phrase “conditions,” sometimes more instructively replaced by “conditions of existence.” Inasmuch as Life is only possible under definite relations of the organism and its medium, the “conditions of existence” will be th

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RECAPITULATION.

RECAPITULATION.

139. The various lines of argument may here be recapitulated. The organic world presents a spectacle of endless diversity, accompanied by a pervading uniformity. The general resemblances in forms and functions are more or less masked by particular differences. The resemblances, it is said, may be all due to kinship, all the living individuals having descended from a primordial cell; and at each stage of the descent the adaptations to new conditions may have issued in deviations from the ancestra

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PROBLEM II. THE NERVOUS MECHANISM.

PROBLEM II. THE NERVOUS MECHANISM.

“All the functions of the nervous system are as dependent upon its structure and nature, as the accurate indication of time upon the construction of the chronometer.”— Prochaska. “Unser Wissen wird nie vollendet, ist und bleibt Stückwerk; dessen Ergänzung das Streben und Hoffen der forschenden Denker bleiben wird für alle Zeit.”— Radenhausen , Osiris . “If we compare the teachings of our books with what Nature is constantly showing, we find there is no agreement between those two sources of lear

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THE NERVOUS MECHANISM.

THE NERVOUS MECHANISM.

1. Our knowledge of mental processes is derived from reflection on our personal experiences, combined with inferences from our observation of other men and animals, under similar conditions. The processes are complex and variable; so complex and variable, that knowledge of their component factors can only be gained through long tentative study, aided by fortunate circumstances which present these factors separately, or at any rate in such marked predominance as to fix attention. This subjective

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THE EARLY FORMS OF NERVE CENTRES.

THE EARLY FORMS OF NERVE CENTRES.

9. In the outermost layer of the germinal membrane of the embryo a groove appears, which deepens as its sides grow upwards, and finally close over and form a canal. This canal is composed of cells all alike. Its foremost extremity soon bulges into three well-marked enlargements, which are then called the primitive cerebral vesicles . The cavities of these vesicles are continuous. Except in position and size, there are no discernible differences in these vesicles, which are known as the Fore-brai

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THE PERIPHERAL SYSTEM.

THE PERIPHERAL SYSTEM.

17. Following the analytical division, we now come to the Peripheral System of nerves and ganglia. The separation, I must often repeat, is purely artificial; but the artifice has conveniences. We separate in the same way the heart from veins and arteries, and the capillary circulation from the arterial. Each nerve has its direct connection with a particular centre, and indirectly with the whole system. It has its circumscribed territory, and individual office. Except in a few cases of anastomosi

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GANGLIA AND CENTRES,

GANGLIA AND CENTRES,

usually spoken of as if they were convertible terms. That this is inexact may be readily shown, and that it is misleading appears in its causing physiologists to credit every ganglion, wherever found, with central functions; and, by an almost inevitable extension of the error, has led to the assignment of central functions to a single ganglionic cell! This is but part of that “superstition of the cell” against which I shall have to protest. I will not here raise the doubt which presses from vari

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CHAPTER II. THE FUNCTIONAL RELATIONS OF THE NERVOUS SYSTEM.

CHAPTER II. THE FUNCTIONAL RELATIONS OF THE NERVOUS SYSTEM.

23. The distinguishable parts of this system are the central axis, the cranial nerves, and the spinal nerves, with the chain of ganglia and nerves composing the Sympathetic. Let us briefly set down what is known of their special offices. Men very early discovered that the nerves were in some way ministrant to Sensation and Movement; a divided nerve always being accompanied by insensibility and immobility in the limb. Galen, observing that paralysis of movement sometimes occurred without insensib

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ORIGIN OF NERVE-FORCE.

ORIGIN OF NERVE-FORCE.

56. After this brief account of Neurility we may pass to the consideration of its origin. Are we to understand that this property belongs to the nerves themselves in the sense in which Contractility belongs to the muscles? or are we to accept the teaching which assigns the origin of “nerve-force” to the ganglia, and regards the nerves simply as passive conductors of a force developed in the cells? 57. It is now many years since I ventured to criticise the reigning doctrine, and to urge the neces

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THE HYPOTHESIS OF SPECIFIC ENERGIES.

THE HYPOTHESIS OF SPECIFIC ENERGIES.

63. One development of the theory of Bell, respecting the different kinds of nerve, has been the still accredited hypothesis that each nerve has a “specific energy,” or quality, in virtue of which it acts and reacts only in one way. The optic nerve, no matter how stimulated, only responds by a sensation of color, the auditory nerve only by a sensation of sound; and so on. This hypothesis, which (as I learn from a correspondent) 107 was originally propounded by Bell himself, was developed and mad

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CHAPTER IV. SENSIBILITY.

CHAPTER IV. SENSIBILITY.

68. The principles laid down in the preceding chapter are equally applicable to the central system. But here greater difficulties await us. We cannot expect traditional views to be easily displaced, when they have taken such hold on the mind, as is the case with regard to Sensibility. To admit that all nerves have a common property, and that their functional relations depend on the organs which they innervate, demands small relinquishment of cherished opinions. But to admit that all nerve-centre

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CHAPTER V. ACTION WITHOUT NERVE-CENTRES.

CHAPTER V. ACTION WITHOUT NERVE-CENTRES.

89. It has long been one of the unquestioned postulates of Physiology that no nerve-action can take place without the intervention of a centre; and as a corollary, that all movement has its impulse—reflex or volitional—from a centre. 115 The postulate rests on the assumption that nerves derive their “force” from their centre. This assumption we have seen to be erroneous. Yet, in consequence of its acceptance, experimenters have failed to notice the many examples of nerve-action independent of ce

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CHAPTER VI. WHAT IS TAUGHT BY EMBRYOLOGY?

CHAPTER VI. WHAT IS TAUGHT BY EMBRYOLOGY?

97. Subject to the qualification expressed in the last chapter, stimulation of muscles and glands involves a neural process in ingoing nerve, centre, and outgoing nerve. These are the triple elements of the “nervous arc.” If muscles were directly exposed to external influences, they would be stimulated without the intervention of a centre; but as a matter of fact they never are thus exposed, being always protected by the skin. Did the skin-nerves pass directly to the muscles underneath, they wou

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DIFFICULTIES OF THE INVESTIGATION.

DIFFICULTIES OF THE INVESTIGATION.

113. So great and manifold are the difficulties of the search, that although hundreds of patient observers have during the last forty years been incessantly occupied with the elementary structure of the nervous system, very little has been finally established. Indeed, we may still repeat Lotze’s sarcasm, that “microscopic theories have an average of five years’ duration.” This need not damp our ardor, though it ought to check a too precipitate confidence. Nothing at the present moment needs more

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THE NERVE-CELL.

THE NERVE-CELL.

120. It is unfortunate that the term nerve-cell is applied to organites of very variable structure. Nerve-cell is a generic term of which the species are many; under it are designated organites in different stages—as infancy, childhood, and manhood are all included under Man. Most commonly by nerve-cell is understood the ganglionic corpuscle, conspicuous in its size and its prolongations, such as it appears in the great centres, and in ganglia. It also designates smaller different organites, som

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THE NERVES.

THE NERVES.

127. We now pass to the second order of organites; and here our exposition will be less troubled by hesitations, for although there is still much to be learned about the structure and connections of the nerve-fibres, there is also a solid foundation of accurate knowledge. Fig. 20.— a , axis cylinder formed by the fibrils of the cell contents, and at a’ assuming the medullary sheath; b , naked axis cylinder from spinal cord. A nerve is a bundle of fibres within a membranous envelope supplied with

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THE NEUROGLIA.

THE NEUROGLIA.

130. Besides cells and fibres, there is the amorphous substance , which constitutes a great part of the central tissue, and also enters largely into the peripheral tissue. It consists of finely granular substance, and a network of excessively delicate fibrils, with nuclei interspersed. Its character is at present sub judice . Some writers hold it to be nervous, the majority hold it to be simply one of the many forms of connective tissue: hence its name neuroglia, or nerve-cement. In the convolut

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THE RELATIONS OF THE ORGANITES.

THE RELATIONS OF THE ORGANITES.

133. In enumerating among the obstacles to research the tendency to substitute hypothetic deductions in place of objective facts, I had specially in my mind the wide-reaching influence of the reigning theories of the nerve-cell. Had we a solidly established theory of the cell, equivalent, say, to our theory of gas-pressure, we should still need caution in allowing it to override exact observation; but insecure as our data are, and hypothetical as are the inferences respecting the part played by

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RECAPITULATION.

RECAPITULATION.

148. At the opening of this chapter mention was made of the besetting sin of the analytical tendency, namely, to disregard the elements which provisionally had been set aside, and not restore them in the reconstruction of a synthetical explanation. Familiar experiences tell us that a stimulus applied to the skin is followed by a muscular movement, or a glandular secretion; sometimes this takes place without any conscious sensation; sometimes we are distinctly conscious of the stimulus; and somet

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THE ENERGY OF NEURILITY.

THE ENERGY OF NEURILITY.

163. Vitality is characterized by incessant molecular movement, both of composition and decomposition, in the building up of structure and the liberation of energy. The life of every organism is a complex of changes, each of which directly or indirectly affects the statical and dynamical relations, each being the resultant of many co-operant forces. In the nourishment of every organite there is an accumulation of molecular tension , that is to say, stored-up energy in a latent state, ready to be

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THE PROPAGATION OF EXCITATION.

THE PROPAGATION OF EXCITATION.

166. Understanding, then, that the propagation of an excitation depends on the state of tension of the tissue, and always follows the line of least resistance, whichever that may be at the moment, we have to inquire whether the transmission takes place only in one direction, from periphery to centre in sensory nerves, and from centre to periphery in motor nerves? By most physiologists this is answered affirmatively. Indeed a special property has been assigned to each nerve, in virtue of this ima

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STIMULI.

STIMULI.

172. Stimuli are classed as external and internal, or physical and physiological. The one class comprises all the agencies in the External Medium which appreciably affect the organism; the other class all the changes in the organism which appreciably disturb the equilibrium of any organ. Although the pressure of the atmosphere, for example, unquestionably affects the organism, and determines organic processes, it is not reckoned as a stimulus unless the effect become appreciable under sudden var

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STIMULATION.

STIMULATION.

176. Passing now from these general considerations to their special application, we may formulate the law of stimulation: Law III. A faint or moderate stimulation increases the activity of the organ; but beyond a certain limit, increase of stimulation diminishes, and finally arrests, the activity. Duration of stimulation is equivalent to increase. A muscle stimulated contracts; if the stimulation be repeated, the muscle becomes tetanized, and in this state has reached its limit; a fresh stimulat

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THE LAW OF DISCHARGE.

THE LAW OF DISCHARGE.

180. The physiological independence of organs, together with their intimate dependence in the organism, and the fact that this organism is incessantly stimulated from many sides at once, assure us a priori that the “waves” of molecular movement due to each stimulus must sometimes interfere and sometimes blend with others, thus diverting or neutralizing the final discharge in the one case, and in the other case swelling the current and increasing the energy of the discharge. We are accustomed to

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THE LAW OF ARREST.

THE LAW OF ARREST.

190. The Law of Arrest is only another aspect of the Law of Discharge, and may be regarded as the conflict of excitations. If a stranger enters the room where a woman lies in labor, there will often be caused a sudden cessation of the uterine contractions. 198 Again, every one knows how the breathing and the beating of the heart are arrested by the idea of danger. The arrest is in each of the three cases only temporary, because when the shock of the new stimulus has caused its discharge (arrest)

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THE HYPOTHESIS OF INHIBITORY CENTRES.

THE HYPOTHESIS OF INHIBITORY CENTRES.

195. The facts and their formulated laws which have just been adduced furnish a sufficient explanation of all the phenomena of arrest which of late years have been detached and assigned to a special mechanism of inhibitory nerves and centres. In spite of the eminent authorities countenancing the hypothesis of a particular set of inhibitory nerves, and particular centres of inhibition, I must confess that the hypothesis appears to me inadmissible; and that I side with those physiologists who hold

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ANATOMICAL INTERPRETATION OF THE LAWS.

ANATOMICAL INTERPRETATION OF THE LAWS.

197. The problem for the anatomist is twofold: First, given the organ, he has to determine its function, or vice versa , given the part of an organ, to determine its functional relation; secondly, given the function, he has to determine its organ. The structural and functional relations of nerves and centres have been ascertained in a general way; we are quite sure that the posterior nerves carry excitations from sensitive surfaces, that the anterior nerves carry excitations to muscles and gland

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PROBLEM III. ANIMAL AUTOMATISM.

PROBLEM III. ANIMAL AUTOMATISM.

“L’organisme le plus complexe est un vaste mécanisme qui résulte de l’assemblage de mécanismes secondaires.”— Claude Bernard. “Les corps vivants sont machines à l’infini.”— Leibnitz. “Noi lamentiamo con Majendie che nel linguaggio fisiologico siensi intruse le preopinioni psicologiche col trascico inevitabile del vocaboli, ai quali codeste preopinioni si trovano legate. Probabilmente questa fu una delle principali cagioni degli errori e degli equivoci anatomofisiologici, da cui non poterono svin

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CHAPTER I. THE COURSE OF MODERN THOUGHT.

CHAPTER I. THE COURSE OF MODERN THOUGHT.

1. Modern Philosophy has moved along two increasingly divergent lines. One, traversed by Galileo, Descartes, Newton, and Laplace, had for its goal the absolute disengagement of the physical from the mental, i. e. the objective from the subjective aspect of phenomena, so that the physical universe, thus freed from all the complexities of Feeling, might be interpreted in mechanical terms. As a preliminary simplification of the problem this was indispensable; only by it could the First Notion of pr

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CHAPTER II. THE VITAL MECHANISM.

CHAPTER II. THE VITAL MECHANISM.

14. No answer can be successfully attempted in reply to the first of the questions which closed the last chapter until we have given precision to certain terms of incessant recurrence. I have often to remark on the peculiar misfortune of Psychology, that all its principal terms are employed by different writers, and are understood by different readers, in widely different senses: they denote and connote meanings of various significance. All physicists mean the same thing when they speak of weigh

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CHAPTER III. THE RELATION OF BODY AND MIND.

CHAPTER III. THE RELATION OF BODY AND MIND.

27. The second question proposed was, In what sense can Feeling be correctly spoken of as an Agent in organic processes? This brings us face to face with a much-debated topic, the relation of Body and Mind; and demands a theoretic interpretation of that First Notion which expresses universal experience, namely, that what I know as Myself is a Body, in one aspect, and a Soul, in the other. What I call my Body is a persistent aggregate of objective phenomena; and my Soul is a persistent aggregate

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CHAPTER IV. CONSCIOUSNESS AND UNCONSCIOUSNESS.211

CHAPTER IV. CONSCIOUSNESS AND UNCONSCIOUSNESS.211

48. Science demands precision of terms; and in this sense Condillac was justified in defining it, “ une langue bien faite .” The sciences of Measurement are exact because of the precision of their terms, and are powerful because of their exactness. The sciences of Classification cannot aspire to this precision, and therefore, although capable of attaining to a fuller knowledge of phenomena than can be reached by their rivals, this advantage of a wider range is accompanied by the disadvantage of

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CHAPTER V. VOLUNTARY AND INVOLUNTARY ACTIONS.

CHAPTER V. VOLUNTARY AND INVOLUNTARY ACTIONS.

61. Much of what has been said in the preceding chapter respecting the passive side of the organism is equally applicable to the active side. Our actions are classed as voluntary and involuntary mainly in reference to their being consciously or unconsciously performed; but not wholly so, for there are many involuntary actions of which we are distinctly conscious, and many voluntary actions of which we are at times sub-conscious and unconscious. I do not propose here to open the long and arduous

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CHAPTER VI. THE PROBLEM STATED.

CHAPTER VI. THE PROBLEM STATED.

71. If the preceding attempt to disengage the question from the ambiguities of its terms has been successful, we shall find little difficulty in rationally interpreting all the facts adduced in favor of Animal Automatism, without having recourse to a mechanical theory of biological phenomena. The objections to that theory are that it employs terms which have very misleading connotations even when they do not denote phenomena of widely different orders; so that the moral repugnance commonly felt

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CHAPTER VII. IS FEELING AN AGENT?

CHAPTER VII. IS FEELING AN AGENT?

78. Descartes having attributed all animal actions to a sensitive mechanism, and indeed all human actions to a similar mechanism, endeavored to reconcile this hypothesis with the irresistible facts of Consciousness—which assured us that our actions, at least, were determined by Feeling. To this end he assumed that man had a spiritual principle over and above the sentient principle. The operation of this principle was, however, limited to Thought; the actions themselves were all performed by the

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PROBLEM IV. THE REFLEX THEORY.

PROBLEM IV. THE REFLEX THEORY.

“Si omnes patres sic, et Ego non sic.”— Abelard , Sic et Non . “Will man bestimmen wo der Mechanismus aufhört und wo der Wille anfängt so ist die Frage überhaupt falsch gestellt. Denn man setzt hier Begriffe einander gegenüber die gar keine Gegensätze sind. Vorgebildet in den mechanischen Bedingungen des Nervensystems sind alle Bewegungen.”— Wundt , Physiologische Psychologie . “Sollte die so durchsichtige Homologie zwischen Hirn and Rückenmark, wie solche sich schlagend in Bau und Entwicklung d

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CHAPTER I. THE PROBLEM STATED.

CHAPTER I. THE PROBLEM STATED.

1. The peculiarity of the Reflex Theory is its exclusion of Sensibility from the actions classed as reflex; in consequence of which, the actions are considered to be “purely mechanical.” No one denies that most of the reflex actions often have conscious sensations preceding and accompanying them, but these are said not to be essential to the performance of the actions, because they may be absent and the actions still take place. It is notorious that we breathe, wink, swallow, etc., whether we ar

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CHAPTER II. DEDUCTIONS FROM GENERAL LAWS.

CHAPTER II. DEDUCTIONS FROM GENERAL LAWS.

23. The evidence is of two kinds: deductions from the general laws of nervous action, and inductions from particular manifestations. The former furnish a presumption, the latter a proof. The central process which initiates a reflex action may be excited by the external stimulation of a peripheral nerve, by the internal stimulation of a peripheral nerve, or by the irradiation from some other part of the central tissue. The last-named stimulations are the least intelligible, because they are so va

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CEREBRAL REFLEXES.

CEREBRAL REFLEXES.

While Theory separated the actions of the cord from those of the brain on the ground of their being at times unconscious and involuntary, Observation disclosed that this distinction could not be maintained. This step was taken by Dr. Laycock in 1840. In a striking paper 247 read by him at the British Association in 1844, he brought together the evidence on which his view was founded. The idea has been adopted and illustrated in the writings of Dr. Carpenter, who now calls the action “unconscious

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DISCRIMINATION.

DISCRIMINATION.

Although this process is usually regarded as purely psychological, it must obviously have its physiological side; we find it in Sensation as in Ideation, and may expect to find it in unconscious as in conscious processes—in a word, in all sensorial processes whatever. Place a bit of marble on your tongue, and it will be touched, but not tasted: the sensations of contact and temperature will excite reflexes, but little or no reflexes from parotid and salivary glands. A difference in sensation has

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MEMORY.

MEMORY.

53. “But discrimination, if not a purely physical process, implies Memory?” No doubt. And what is Memory—on its physiological side—but an organized tendency to react on lines previously traversed? As Griesinger truly says: “There is Memory in all the functions of the central organs, including the spinal cord. There is one for reflex actions, no less than for sense-images, words, and ideas.” Gratiolet makes a similar assertion. 266 Indeed if, as we have seen, reflex actions are partly connate, an

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INSTINCT.

INSTINCT.

54. If we can detect evidences of Volition and Instinct in the absence of the brain, our thesis may be considered less questionable. And such evidence there is. Goltz decapitated a male frog (in the pairing season), and observed that it not only sought, grasped, and energetically embraced a female, but could always discriminate a female from a male. Thus when a male frog closely resembling a female in size and shape was presented to this decapitated animal, he clasped it, but rapidly let it go a

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THE MECHANISM OF INSTINCT.

THE MECHANISM OF INSTINCT.

Were we dealing with an ordinary mechanism, and the disturbances produced in its actions by the removal of any part, we should attribute all observed effects to interference with the conditions of dependent sequence : we should infer that the actions were imperfectly performed, or wholly abolished, because their requisite mechanical conditions were disturbed. Let us be equally precise in dealing with the physiological mechanism. If we have deprived it of an organ in which certain combinations ar

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ACQUISITION.

ACQUISITION.

80. Not only may Discrimination and Instinct be manifested in the absence of the brain, but even the acquisition of new modes of reaction, such as are classed under Learning through Experience. The objection is sometimes urged that animals without their brains only manifest single reactions on stimulation—the pinched foot is withdrawn, and then remains motionless until again pinched. But although the stimulation does not excite a consecutive series of movements, because there is no cerebrum to r

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CHAPTER IV. NEGATIVE INDUCTIONS.

CHAPTER IV. NEGATIVE INDUCTIONS.

84. I fancy some reader exclaiming: “All your reasoning, and all your marshalled facts, are swept away by the irresistible evidence of human patients with injured spinal cords, whose legs have manifested reflex actions, and who nevertheless declared they had no sensation whatever in them. We can never be sure of what passes in an animal; but man can tell us whether he feels an impression, or does not feel it; and since he tells us that he does not feel it, cannot , however he may try , we conclu

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