160 Leyton and Sherrington 



It may be noted that among the chimpanzees we examined were two 

 very young ones, the younger of them, though in good nutritive con- 

 dition, weighing only 2'240 kilog. In one of these we found a cortical 

 differentiation of the linger movements at least as great as in any other of 

 the anthropoid brains we explored. In this animal we obtained from 

 appropriate points in the cortex isolated movements of the little linger, 

 both isolated flexion and isolated extension ; also isolated movement of 

 the 2nd toe, both of flexion and of extension ; also movement of the 2nd 

 and 3rd toes without movement of the other toes. The animal was so 

 young as to be infantile ; it was fed from a sucking-bottle, and had the 

 petulance and habits and cries of a very young animal. 



Epilepsy. — Prolonging the faradisation, especially strong faradisation, 

 of a spot in the motor surface usually induces not only a considerable 

 " march " or sequence of responsive movement, but also, as is well known, 

 an epileptiform convulsion. Our experiments were not directed toward 

 observation of these, but we induced such eflects from time to time. We 

 found them easily provoked in the anthropoid, but not obviously more 

 readily than in small monkeys such as macacus and calothrix. A differ- 

 ence in the two cases seemed the greater relative ease with which in the 

 anthropoid an epileptiform convulsion could be evoked in this or that 

 small region of musculature without the convulsion spreading beyond that 

 part. Thus it could be evoked in the index flnger, in the angle of the 

 mouth, or in the toes, and remain confined to the field in which it started : 

 such restriction is, in our experience, quite uncommon in macacus or 

 calothrix. 



" Epilepsy " was evoked rea.dily in the " baby " chimpanzees coming 

 under observation ; it seemed neither more nor less readily obtained in 

 them than in the grown specimens. On the other hand, the ease with 

 which it was evoked, and the tendency for it to occur in the course of an 

 experiment, appeared to us to vary distinctly in dift'erent individuals ; in 

 some individuals stimulation of duration and intensity too small to evoke 

 it usually, tended to evoke it from the very beginning of the experiment, 

 and that tendency continued throughout the experiment. 



It may be of interest to remark that in ablation experiments with 

 small monkeys we have sometimes found a collodion dressing applied to 

 the scalp over the removed area of bone produce severe epileptiform 

 convulsions, which ceased at once on removal of the dressing. The 

 shrinkage of the collodion in such cases caused the dressing to press upon 

 the scalp and underlying bi'ain, the surface of the dressing over the 

 removed piece of skull becoming flat or slightly concave outward. 



A few general remarks may be offered in regard to certain of the 

 movements evoked and the representation of separate motile parts in the 

 cortex. We follow for convenience the order taken in the foregoing index 

 to the motor responses listed. 



