Nov. 30, 1876] 



NATURE 



95 



But restricting the explanation to movements, is it 

 not a relinquishment of the hypothesis of voluntary 

 motor centres ? Is it not an invocation of the hypo- 

 thesis of peripheral incitation ? Observe this, more- 

 over : Dr. Farrier restricts his explanation to the move- 

 ments which have been automatically organised in the 

 corpora striata. All actions not become automatic are 

 impossible after removal of the cortical centres. "It may 

 confidently be asserted," he says, "and perhaps it may 

 one day be resolved by experiment, that any special tricks 

 of movement which a dog may have learnt would be 

 effectually paralysed by removal of the conical centres." 

 Weil, since this was written, experiment has decided the 

 point. By an ingenious method of washing away cerebral 

 substance, Goltz has been able to greatly diminish the 

 disastrous effects of operation, and thus preserved the 

 animals for weeks, in the course of which he observed an 

 almost complete restitution of the lost functions. One of 

 the striking cases recorded by him (Pfliiger's Archiv, 

 xiii. 31) is that of a dog who had been taught to " give 

 the paw " on command. When the surface of the left 

 hemisphere had been washed away there was at first a 

 complete destruction of the power to give the right paw ; 

 and the dog when urgently called upon to give it, looked 

 wistful, and ended by stretching out the left paw. Had 

 the dog died within six days after the operation this might 

 have been cited as proof of the destruction of a voluntary 

 centre ; but the dog lived, and on the eightli day began 

 to give the right paw when asked, and a month afterwards 

 gave it as readily as before the operation. 



Second Head. — Under this head we may consider the evi- 

 dence adduced for the existence of definitely circumscribed 

 areas, and definite spots within those areas. Dr. Ferrier's 

 pages are very instructive on this point, but not, I think, 

 competent to force his conclusion when they are con- 

 fronted with Goltz's experiments, which show that the 

 paralysis of sensation and motion cannot reasonably be as- 

 signed to the destruction of particular spots, because the 

 paralysis is dependent solely on the amount of substance 

 washed away, and not at all on the localities. Add to which 

 the fact just insisted on, that the paralysis is temporary. 

 Dr. Ferrier believes that his experiments prove the distinct 

 localisation of motor centres. For example, he produces 

 inflammation and suppuration in one place, and observes 

 spasms followed by paralysis of motion in the whole of 

 one side of the body. This is urged in proof of motion 

 being affected without affection of sensation. On exami- 

 nation, however, it seems to me only to prove the effects 

 of disturbance ; and this the more decisively, because he 

 admits than when instead of an irritatijtg suppuration 

 there is extirpation of the centre, the paralysis quickly 

 disappears. "In these experiments," he adds, "the 

 power of movement alone was destroyed, sensation re- 

 maining acute and unimpaired." This is very ambiguous. 

 Sensation elsewhere — on the other side of the body — was 

 unimpaired ; but so was power of movement there. In 

 the paralysed limbs there was no sensation. 



Let us now turn to a sensational centre : and we will 

 select that of Vision, because the experiments are here 

 most striking. Destruction of the " angular gyri:s " on 

 one side causes blindness in the opposite eye. But this 

 effect is temporary, and begins to subside the next day 

 (p. 165). One would imagine that in presence of such 



observations, the fact of blindness would be attributed to 

 Disturbance, not Removal of Function ; and the recovery 

 of vision to the subsidence of the disturbance. Dr. Ferrier 

 interprets the recovery as due to the compensatory action 

 of the centre in the other hemisphere (p. 169). But this is 

 to invoke the Law of Substitution (which he has success- 

 fully refuted), and leaves unexplained why the compen- 

 satory action did not manifest itself from the first. The 

 experiments of Goltz seem to me conclusive as to the 

 observed blindness being merely the effect of disturbance ; 

 not only does the vision gradually return, but is proved 

 not to depend on the conpensatory action of the intact 

 centre, because it reappears even in an animal deprived 

 of the other eye. That is to say a dog, with only one 

 eye, had almost the whole of one hemisphere washed 

 away, so that on the one side it had no optical apparatus, 

 on the other no visual cortical centre — yet it showed un- 

 mistakable evidence of being able to see. Observe the 

 dilemma: either there is a complete decussation of the 

 optic nerves, so that each hemisphere is the sole centre 

 for one of the eyes j or the decussation is pattial, so that 

 each hemisphere is a centre for both eyes. In the first 

 case destruction of the one hemisphere should produce 

 absolute and permanent blindness in one eye— and this 

 is disproved by experiment. In the second case destruc- 

 tion of one hemisphere should produce partial blindness 

 in both eyes — and this also is disproved by experiment. 

 Or, finally, the visual centres are not in the hemispherer, 

 so that destruction of the hemispheres is not destruction 

 of vision — and this is what experiment proved. 



Third Head. — I must be very brief on this point — 

 namely, that very various effects ensue on excitation of 

 one and the same spot. If we regard the cortex as a 

 peripheral surface of excitation there is nothing myste- 

 rious in the various effects produced by reflexes from it — 

 as from the skin ; but if we regard it as a collection of dis- 

 tinct sensory and motor centres, there is great difficulty in 

 reconciling the results of observation. For example, the 

 so-called voluntary centres for movements of the limbs and 

 tail are found by Bochefontaine to be centres of salivary 

 secretion. In his memoir in the Archives de Physiologic 

 (1876, No. 2, p. 169), the last-named experimenter sums 

 up the results of his observations thus— that the hypo- 

 thesis of cortical voluntary centres would lead to the 

 conclusion that the same spot was the centre for volun- 

 tary movements in a limb, and involuntary contractions 

 of the bladder and spleen, as well as dilatation of the 

 pupil. 



My space is exhausted, and I have not been able to do 

 more than criticise the main topic of Ur. Ferrier's book — 

 and this not with the fulness which its importance de- 

 mands. But if I have shown grounds for regarding the 

 hypothesis of voluntary centres in the cortex as at any rate 

 far from proved, and in doing so have had to adopt an 

 antagonistic attitude throughout my review, I should not 

 be just to him, nor to my own feelings of gratitude, if 

 I did not, in concluding, express a high sense of the value 

 of his work, full as it is of suggestions, and rich in 

 facts, which no counter-facts can set aside. It wilt long 

 remain a storehouse to which all students must go for 

 material. It may be the starting-point of a new anatomy 

 of the brain. 



George Henry Lewes 



