March lo, 1887] 



NATURE 



439 



I have myself frequently obsen-ed recovery, to all appear- 

 ance complete. It appears to mc that the idea expressed 

 by the term " concentration of function " harmonises 

 much more fully with our existing knowledge of the facts 

 relating to this question than the more inflexible phrase 

 "localisation.' 



It is time, however, to turn to the edition which lies 

 before us. Dr. Ferrier, in his preface, tells us that the 

 book has been almost entirely re-written, and, in point of 

 fact, so much has been added and modified as to consti- 

 tute this edition, in many respects, a new book. But the 

 principal teachings of the original- those to which the 

 book from the first owed its chief interest — the doctrines, 

 namely, therein advocated regarding the localisation of 

 cerebral functions, are, it is claimed by the author, main- 

 tained in all essentials unchanged. Since it is to the 

 exposition of these doctrines, and especially of the experi- 

 mental facts upon which they rest, that the student of 

 physiology or psychology would naturally first turn, in 

 order to disco\er what that is new may have been adduced 

 in support of the Ferrierian teachings, and in what manner 

 the hostile attacks which have been directed against them 

 are met by their author, no apology is needed if we devote 

 our attention first and chiefly to those parts of the book 

 which deal with this important question. 



After it had been found impossible to deny the correct- 

 ness of the facts regarding electrisation of the cortex of 

 certain regions of the brain, a vigorous onslaught was 

 made from various quarters upon the method of experi- 

 mentation. It was especially contended (by Dupuy and 

 others) that the movements produced by this method are 

 really due, not to excitation of the cortex cerebri itself, but 

 lo conduction of the current to the basal ganglia (corpora 

 striata). But a single new fact entirely overthrows the 

 last remnant of this objection, since it has been shown 

 (by Franck and Pitres) that similar movements may be 

 caused by mere mechanical stimulation of the cortex 

 (p. 228). Indeed, the same observers entirely deny that 

 the basal ganglia respond at all to direct electrical excita- 

 tion, a statement which we shall afterwards see is not, 

 however, accepted by Dr. Ferrier. 



In the review above alluded to, Mr. Lewes alleges two 

 ])rincipal facts against the doctrine that the gray matter 

 of the cerebral cortex is directly excitable, viz. : (i) the 

 fact that only the electrical current causes an excitation, — 

 mechanical and chemical stimuli have no such effects, 

 because they cannot pass through the cortex to reach the 

 white substance ; (2) what he terms the " decisive experi- 

 ment" of Dr. Burdon Sanderson. "If that part of the 

 surface of the hemisphere which comprises the active 

 spots is severed from the deeper parts by a nearly hori- 

 zontal incision made with a thin-bladed knife, . . the 

 result is the same as when the surface of the uninjured 

 organ is acted upon" (Proceedings of the Royal Society, 

 No. 153). But we have just seen that, under suitable 

 conditions, the cerebral surface may be excited mechanic- 

 ally ; and, with respect to the second fact, I imagine that 

 Dr. Sanderson would now be the first to admit that his 

 results were due either to imperfect severance or to the 

 spreading of a current of too great intensity. 



.Moreover, the study of the characters of the contrac- 

 tions which result from excitation of the cortex has tended 

 to show that its excitation is indeed a stimulation of 

 centrifugally discharging nerve-centres, and in conformity 

 with this view it is found that destruction of the cortex 

 in the excitable regions is followed not only by immediate 

 paralysis of the parts in which movement is evoked on 

 excitation, but also by speedy degeneration of the effer- 

 ent nerve-fibres. The arguments upon this point are set 

 forth briefly, but clearly, by the author (pp. 231-33). 



With regard to the results of localised excitation of the 

 cortex (in the monkey), some modifications which are not 

 wholly unimportant have been introduced ; but to obtain 

 these the author appears rather to have again consulted 



his original memoir (Proc. Roy. Soc, No. 161, 1875) than 

 the results of any new experimental investigations. The 

 facts that the excitable region extends over the margin of 

 the hemisphere to include the marginal gyrus upon the 

 mesial surface, and that this part of the excitable region 

 is associated with movements of the leg and trunk, had 

 not been definitely determined at the time of publication 

 of the first edition, but are duly recorded here (p. 245). 



The general correctness of Dr. Ferrier's statements 

 regarding the results of localised excitation of the brain 

 in the monkey (and, from its resemblance to the human 

 brain, these will be those of chief interest to most readers' 

 seems at the present time to be universally admitted. I 

 have myself so frequently had the opportunity of verifying 

 them as to have no doubt of their general applicability. 

 But the inferences which he has drawn from the results 

 of excitation have not, as we shall presently see, been 

 allowed to remain unquestioned. 



The method of localised ablation is of yet more import- 

 ance for the determination of the functions of the cortex 

 than that which we have just considered. In carrying 

 out this method, the necessity of strict adherence to 

 Listerian precautions is demonstrated when we com- 

 pare the results which were obtained in the first 

 instance by Dr. Ferrier himself, and recorded in the 

 first edition of this book, with those which have been 

 yielded by the antiseptic method in the hands of Prof 

 Yeo and himself, in a series of experiments undertaken 

 with the express object of testing the applicability of that 

 method to brain-surgery, several of which experiments 

 are recorded in this edition. The path which their 

 experiments indicated has since been trodden by my 

 colleague Mr. Horsley and myself, and it is to- day a 

 beaten track leading to previously undreamedof possi- 

 bilities in surgical science. The fact that the brain can 

 be as effectually searched with a view to the discovery 

 and removal of a tumour as any other part of the human 

 body is an advance of vast extent — a boon to suffering 

 humanity of incalculable value. And that this boon has 

 been acquired, could have been acquired, solely as the 

 result of experiments upon animals, is a fact which may 

 well make the most frenzied of anti-vivisectors pause ere 

 he would deny to his fellow-men the opportunity of 

 acquiring benefits of such inestimable worth ! 



At the present time it is admitted, even by those phy- 

 siologists who, like Goltz, have been hitherto accounted 

 the most strenuous opponents of the doctrine of cerebral 

 localisation, that the results of localised extirpation of 

 the cortex vary with the part removed. These results 

 consist of a loss or diminution in the power of voluntary 

 action of different groups of muscles, or of a loss or 

 defect in the appreciation of sensory impressions (but, 

 according to some observers, both volition and sensibility 

 may be at the same time aftected by the destruction of 

 certain parts) : lastly, from experiments upon some parts 

 of the hemisphere, it may happen that no effect appre- 

 ciable to the observer is obtained. With respect both to 

 these results and those obtained by excitation. Dr. Ferrier, 

 in the first edition of this work, took up certain positions 

 which have in the meanwhile been vigorously assailed 

 from various quarters. These positions are, in the present 

 edition, for the most part defended by the author with no 

 less vigour, although one or two have been somewhat 

 shifted, and one, at least, altogether abandoned. 



in order to make clear these positions to those readers 

 of Natuije who may not have followed closely the con- 

 troversies which have been carried on during the past 

 fifteen years regarding this subject of cerebral localisa- 

 tion, it will be necessary briefly to describe, with the aid 

 of a diagram, the main features of the external configura- 

 tion of the monkey's brain (every fissure and convolution 

 in which is represented in the human brain). It will then 

 be easy to indicate the regions to which special functions 

 were originally ascribed by Dr. Ferrier, the modifications 



