March 17, 1887] 



NATURE 



465 



involved. As for the angular gyrus, the author seems 

 now to admit that the blindness of the opposite eye which 

 he has obtained on destroying that convolution is quite 

 temporary, not, indeed, persisting for more than an hour 

 or two after the operation. Nevertheless, he infers that 

 ihis loss of vision which he describes is due to the fact 

 that the angular g>rus is concerned with the apprecia- 

 tion of diifct or cenlral \'\%VL?\ impressions. I ha\e myself 

 failed to obtain evidence either of permanent or temporary 

 visual disturbances as the result of destruction of the gray 

 matter only of one or both angular gyri ; and 1 confess it 

 is to me somewhat surprising that an experimentalist so 

 experienced, and a reasoner so clear-sighted, as Dr. Ferrier, 

 should have attempted to erect a theory of such import- 

 ance upon a foundation so insecure ! 



(3) A similar idea arises in one's mind when one con- 

 siders the evidence which the author has to bring forward 

 t>f the localisation of the auditory centre in the superior 

 temporo-sphenoidal convolution. l_if course, if this be the 

 case, it must follow that bilateral removal of this gyrus will 

 produce complete and permanent deafness. According to 

 IJr. Ferrier, this is actually what happens ; but there is only 

 one case followed by complete recovery from the immediate 

 eflfects of the operation which he is able to quote in support 

 of that statement. This case is that of a monkey which was 

 exhibited to the International Medical Congress in London 

 in 1S81, and the animal certainly appeared to be deaf, for 

 it in no way reacted to a loud noise, such as the report of 

 a pistol fired near its head. But, convincing as this test 

 seemed at the time to most of those present, I may here 

 remark that a test of this character is of little or no value 

 when applied to monkeys. For a perfectly normal monkey, 

 if its attention or curiosity is excited in any way, and 

 especially if it is brought into a strange room and sur- 

 rounded by strange faces, will often give not the slightest 

 sign of perceiving even a loud sound, such as the report 

 of a pistol, when such sound is suggestixe of no ideas. 

 On the other hand, a sound which is habitually asso;iated 

 with an emotional idea, ^_g-. the noise made by the approach 

 of a hostile companion, or a footstep which is associated 

 with the expectancy of food, will generally be instantly 

 reacted to. It is true that Dr. Ferrier, in the case men- 

 tioned, has not relied entirely upon the negative result 

 obtained from the pistol-report, but expressly mentions 

 other tests as having been applied by him. One remark 

 which he makes is, however, very significant : " Occasion- 

 •illy a doubt was raised as to whether the absence of 

 reactio.i to sounds was absolute." 



I have always been inclined to think that Dr. Ferrier, 

 in localising the auditory centre exclusively in this con- 

 volution, has relied too much upon this single case — 

 especially since his deductions therefrom have not been 

 supported by the results of other experimentalists. Lu- 

 ciani, in particular, insists upon the fact that extensive 

 destruction of the temporo-sphenoidal lobe is necessary 

 in order to produce deafness, and that even then the loss 

 of hearing is not permanent. This statement I can myself 

 fully corroborate. I have recently, in conjunction with Dr. 

 Sanger Brown, entirely destroyed the superior temporo- 

 sphenoidal gyrus on both sides in several monkeys, and 

 in not one of them has there been any appreciable loss or 

 impairment of hearing. On the other hand, when the 

 lesion has involved not only the superior gyrus but also 

 the greater part of the lobe there has in one or two 

 instances seemed to be at first, not an entire loss, but a 

 diminution of the power of appreciating auditory sensa- 

 tions — this condition, however, being recovered from after 

 a few days. 



I am aware that in locating the auditory centre in the 

 superior temporo-sphenoidal gyrus Dr. Ferrier does not 

 rely alone upon the result of extirpation, but adduces 

 also the movements of the ear and eyes which follow 

 electrical excitation as evidence that a subjective auditory 

 sensation is thereby evoked. Taken by itself this is no 



evidence at all, for similar movements may be obtained 

 from excitation of totally different portions of the cere- 

 brum, to say nothing of the cerebellum and of the lower 

 nerve-centres. It only becomes evidence as corroborating 

 the eliect of extirpation. But a single " negative instance " 

 is sufficient to overthrow the hypothesis that the auditory 

 centre is situated in the superior temporo-sphenoidal con- 

 volution alone, and would outweigh many "positive 

 instances." We have, however, only the one well-recorded 

 " positive instance " of Dr. Ferrier (and this was not alto- 

 gether free from doubt) as against several " negative 

 instances " (those of Munk, Luciani, and ourselves ; which 

 last have not yet been published, and could not, therefore, 

 be taken into account by Dr. Ferrier). It is probable, 

 therefore, that Dr. Ferrier's inference is too exclusive, and 

 that other parts of the temporo-sphenoidal lobe]must be 

 included in the auditory centre.' 



(4) The view that tactile sensibility is localised in the 

 hippocampal region has naturally been attacked by those 

 who hold that it is to the Rolandic region that the per- 

 ception of this and other forms of sensibility are to be 

 referred. It would not appear, however, that they have 

 taken the trouble to repeat Prof Ferrier's experiments 

 upon this region, so that his position can hardly be said 

 to have been seriously assailed. On the other hand, it 

 has received both corroboration and extension from the 

 experiments of Mr. Horsley and myself, the results of 

 which were shown to Dr. Ferrier, and the conclusions 

 arrived at fully concurred in by him (pp. 340-45). These 

 experiments showed in the first place that extensive 

 destruction in the hippocampal region, especially of the 

 posterior part of the hippocampal gyrus, is followed by 

 hemiansesthesia, which is not, however, of a permanent 

 character, but disappears after a few days ; and further, 

 that destruction or injury of the gyrus fornicatus (which, 

 as Broca showed, is to be regarded as a direct extension 

 around the corpus callosum of the hippocampal gyrus (see 

 Fig. 2), produces still more marked and far more perman- 

 ent symptoms of a like kind. 



(5) and (6) With regard to the cerebral localisation of 

 the functions of taste and smell, the author in this edition 

 brings forward no new proofs of an experimental nature. 

 But he adduces and quotes evidence from comparative 

 anatomy to show, not only that in animals in which the 

 sense of smell is largely developed (the " osmotics " of 

 Broca) the hippocampal lobule is greatly developed, but 

 also that the development of the anterior commissure, 

 especially of its posterior division, goes hand in hand 

 with that of the hippocampal lobule, and its internal ex- 

 tension, the nucleus amygdala;, and is therefore to be 

 regarded as a commissure of the olfactory centres. The 

 evidence in the first edition regarding the localisation of 

 taste-perceptions was of the scantiest description, and has 

 been in no way subsequently strengthened, and it is neces- 

 sary that further experiments should be made upon the 

 subject with the view of testing the opinion which the 

 author has with all caution put forward on the subject. 



(7) Upon the special functions of the pre-frontal lobes, 

 or whether any function is in fact specially concentrated 

 in this part of the brain, very little light has been thrown 

 by the researches of the past fifteen years. There is a 

 very prevalent idea that intellectual capacity goes hand 

 in hand with the development of this region, an idea 

 which has existed from the time of the old Greeks, although 

 it was not apparently shared by peoples of yet more 

 ancient civilisation. The idea does not, however, appear 

 to receive any confirmation from the experimental method. 



' Dr. Ferrier is mistaken in suppoiing (r/V/f p. 310) that the results of the 

 experiments of Mr. Horsley and myself cjrfirm his conclusions regarding 

 the localisation of the auditory centre in the superior temporo-sphenoidal 

 gyrus. The error seems to have ar.sen from the misunderstandingof averbal 

 communication. What we did find in one or two cases was that the whole of 

 the tcmporo-spheno'.dal lobe exclusive of the superi )r gyrus might be removed 

 on both sides without loss of hearing— not the converse, that hearing was 

 abolished on destroying only the superior gyri on both s.des. Indeed, we 

 did not in any single instance perform this Inst experiment. 



