working diligently at the kindred question of the localization of brain functions. The leading scientific authorities in the second quarter of this century unanimously declared themselves against the hypothesis of localization in any form. Flourens, Magendie, Longet, and other distinguished writers pronounced, on the strength of numerous experiments and observations, that scarcely any particular portion of the cerebral substance is essential to the performance of any particular psychical operation. Consequently, the classical Physiology from 1820 to 1870 proclaimed that the brain as a whole was the single organ of the mind, that the quantity, not the locality, of the brain which is destroyed affects mental activities, and that the degree of imbecility induced is, roughly speaking, in proportion to the amount of cerebral matter removed.2

Some experiments, however, of the German physiologists Fritsch and Hitzig, in 1870, threw serious doubts on the then prevalent doctrine, and a new movement of research, which still continues, was initiated, with the result of completely overthrowing the old teaching. By a series of elaborate experiments on the brains of dogs, monkeys, and other animals, Hitzig, Ferrier, Munk, Luciani, and others, have established a fairly definite theory of localization of "motor-centres ”—that is, of areas in the cortex of the brain the irritation of which produces movements in particular limbs. It is 'On peut retrancher, soit par devant, soit par derrière, soit par en haut, soit par côté, une portion assez étendue des lobes cérébraux, sans que leurs fonctions soient perdues. Une portion assez restreinte de ces lobes suffit donc à l'exercise de leurs fonctions. A mesure que ce retranchement s'opère, toutes les fonctions s'affaiblissent et s'éteignent graduellement. . . . Enfin, dès qu'une perception est perdue, toutes le sont; dès qu'une faculte disparait, toutes disparaissent." (Flourens.) Cf. Bastian, Brain as an Organ of Mind, p. 520.

2 Sur des chiens, des chats et des lapins, chez un grand nombre d'oiseaux, j'ai eu occasion d'irriter mécaniquement la substance blanche des hémisphères cérébraux; de la cauteriser avec la potasse, l'acide azotique, le fer rouge, &c.; d'y faire passer des courants électriques en divers sens, sans parvenir jamais à mettre en jeu la contractilite musculaire: même résultat négatif en dirigeant les mêmes agents sur la substance grise des lobes cérébraux." (Longet.) Cf. Surbled, Le Cerveau, p. 149.

also claimed by the advocates of localization that the cerebral "centres" corresponding to the various senses have been discovered. This part of the theory, however, is much more energetically contested. As regards the nature, the locus, or even the existence of the physical concomitants of the higher mental activities absolutely nothing is at present known.

In the study of cerebral functions three chief lines of investigation present themselves: (a) Experiment by stimulation and extirpation of particular portions of the brains of the lower animals; (b) Cerebral Pathology, or the science which deals with brain diseases in human beings; and (c) Comparative Anatomy and Histology, which examine the structural connexions of different parts of the brain and nervous system throughout the animal kingdom. Thus, the stimulation by electricity of certain areas in the cortex of the brain of dogs, monkeys, and other animals, is found to excite movements in the neck, arms, fingers, legs, tongue, &c. Conversely, the extirpation or destruction of these same portions of the brain temporarily suspends the power of movement in the the corresponding limb. Again, post-mortem examinations often show that atrophy and disease of the cerebral substance of these areas have been concomitant with paralysis of the appropriate limb. Moreover, several cures of such local paralysis have also been already effected by the venturesome remedy of trepanning the skull and removing tumours found to exist where anticipated.3 Finally, comparative study of the structure of the brain in different species of animals tends to establish the identity of the "areas constituting the "motorcentres of the several limbs, and it also shows that the number and definiteness of such "areas increase in proportion as we rise in the animal kingdom and examine more highly specialized brains.

By means of these various methods of research Dr. Ferrier has succeeded in mapping out over a dozen "motor-centres" on the surface of the brain. They are nearly all situated in the vicinity of the summit of Cf. Surbled, Le Cerveau, pp. 239, seq.

the cerebrum about mid-way between the forehead and back of the skull-technically, in the gyri centrales and the lobulus paracentralis. The cerebral "areas" of the senses he locates mainly in the occipital or hind portion of the brain. The frontal region is as yet "silent,' that is, not responsive to stimulation; and, accordingly, there is no evidence for the assignment to it of any particular functions. Some writers on this account speak of this portion of the cerebrum in a vague way as the "seat of general intelligence." We have already shown the absurdity of attempting to conceive the higher faculties as situated in or exerted by means of bodily organs. It is possible, however, that this part of the cerebrum may supply the material basis for the internal sensuous faculties upon which intellectual activity is more immediately dependent. Still, the fact that serious lesions involving the destruction of extraordinarily large quantities of brain in this region without appreciably affecting any mental operations frequently met with, whilst apparently slight injuries in other districts have often produced profound intellectual derangement, shows the precarious character of even this conjecture.4

are

The "motor-centre" is usually found on the side of the head opposite to the bodily member to which it is specially related; but speech, and other psychical operations not belonging definitely to either side of the organism are generally dependent on physical processes in the left hemisphere, except in the case of left-handed persons, who, it is said, are "right-minded" or rather "right-brained." The disease of aphasia in righthanded persons is, as a rule, accompanied by a lesion in the third left frontal convolution. It seems also fairly proven that symmetrical portions of the brain. in the right and left hemispheres are capable of performing similar functions, and it is chiefly-though not exclusively-in the relations subsisting between these corresponding parts that we find exhibited the law of substitution, which constitutes such a serious objection to all theories of localization.

♦ Cf. Ladd, Physiological Psychology, pp. 265—268, 296, 297.

On this general fact, together with exceptional cases presented by Pathology, the case of the opponents of localization mainly rests. It is true, say they, that irritation of a motor-area excites movement in the corresponding limb, and conversely, the extirpation or destruction of this part of the brain temporarily extinguishes or enfeebles the power of movement; but, nevertheless, if the animal be kept alive, it may after a few days recover complete use of the member again. In other words, some new portion of the cerebrum is capable of adopting the suspended function.5 The part most fitted to do so seems to be in the first place the symmetrically corresponding area on the other hemisphere, and then the cerebral substance immediately surrounding the damaged centre. In addition to this difficulty post-mortem examinations have revealed several cases in which a very large part of one side of the brain, and even a not inconsiderable portion of both were atrophied or decayed, although no derangement in psychical operations, or in the action of the corresponding limbs, had been noticed during life.

These objections indicate clearly how imperfect our knowledge of the relations between the brain and psychical action still is, and they also show how little foundation there is for the vaunting tone of certain materialistic scientists. At the same time we do not think they are conclusive against the doctrine of localization in every form. They indisputably demonstrate that the "centres" are not instruments of an absolutely fixed and permanent character like the external senseorgans. But they do not disprove the statement that

The eminent physiologist Goltz is perhaps the most distinguished assailant of localization theories. According to him, "It is not possible, by extirpating any amount of the substance of the cortex on either side, or on both sides, to produce a permanent laming of any muscle of the body, or a total loss of sensibility in any of its parts. It is, however, possible thus to reduce an animal to a condition of almost complete idiocy. . . . No part of the cortex of the brain can, then, be called the exclusive organ or centre of intelligence or feeling; but the psychical functions are connected with all of its parts." (Cf. Ladd, op. cit. p. 298.)

the various sentient and motor operations of the soul are, in ordinary conditions, specially dependent on particular parts of the brain, whilst the evidence on the other side makes this latter assertion well-nigh incontrovertible. They establish, however, that the principle which dominates the living organism has, within certain limits, the power of adapting to its needs and employing as its instruments other than the normal portions of the cerebrum.6

Although this question of brain functions pertains rather to Cerebral Physiology than to Psychology, we have deemed it advisable to treat the subject at some length here. The statement that the progress of Physiology has discredited or disproved the doctrine of the spirituality of the soul, is so frequently to be met with that it is extremely desirable the student should have at least a general notion of the character and value of the most recent investigations in Cerebral Physiology. Vague sweeping assertions, especially when uttered by men distinguished in Physical sciences, often give rise to a completely mistaken idea of the nature of the "recent advances in Physiology." We trust that our sketch of the subject will enable the reader to judge the worth of such materialistic decla

rations.

6 The original researches of Dr. Ferrier on this subject are to be found in his work, The Functions of the Brain. (2nd Edit. 1886.) Dr. Bastian's volume, The Brain as an Organ of Mind, c. x. contains a history of theories of Phrenology and Localization. There is a long account and an absurdly exaggerated estimate of Gall in Lewes' History of Philosophy. It is lamentable that these writers cannot discuss a scientific question without the introduction of materialistic dogmatism as unjustifiable as it is irrelevant. A brief but very good treatment of the question of localization is to be found in the article Brain" in Chambers' Encyclopedia (New Edit. 1888); a lengthier account is given under "Physiology," Encyc. Brit. (9th Edit. 1885.) The substance of Ferrier's work is given in Professor Calderwood's Relations of Mind and Brain (1879), pp. 79-122. The best and most impartial handling of the subject, however, which we have seen is that by Ladd, op. cit. Pt. II. cc. i. ii. (1887.) A clear and interesting account of this question, with an admirable treatment of other physiological topics bordering on Psychology, are given in Dr. Surbled's excellent little work, Le Cerveau. (Paris: Retaux-Bray, 1890.)