206 Leyton and Sherrington 



usual on having to return to his cage after feeding and playing. Is finally 

 pacitied on being given more grapes than customary allowance. Is certainly 

 as vociferous as ever ; seems to employ quite as wide a range of various 

 sounds as before. Calls and shouts when alone or when watched from a 

 distance." 



April 12. — Certainly not the slightest reduction of animal's vocalisa- 

 tion, nor any apparent change in it. Appetite good. Wound healing well ; 

 but animal seems more excitable than before the operation. 



April 14. — Same condition; still very excitable; wound healing well. 



April 16. — Same as before ; wound nearly healed. 



April 17. — Animal has torn otT its dressing, and torn up skin flap; 

 some haemorrhage. Re-dressed. 



April 20. — Wound infected: animal killed under chloroform. 



Remarks on Foregoing Ablation-Experiments. 



Owing to their lesser remoteness from human type it seems more 

 possible in regard to the anthropoid than to monkeys such as macaque 

 to infer the animal's mental attitude at various times. A point which 

 impressed us repeatedly was the seeming entire ignorance on the part 

 of the animal, on its awakening from an ablation-experiment, of any dis- 

 ability precluding its performance of its willed acts as usual. Surprise 

 at the failure of the limb to execute what it intended seemed the animal's 

 mental attitude, and not merely for the hrst few minutes, but for many 

 hours. It was often many hours before repeated and various failures to 

 execute ordinary acts contributory to climbing, feeding, etc., seemed to im- 

 press gradually upon the animal that the limb was no longer to be relied upon 

 for its usual services. The impression given us was that the fore-running 

 idea of the action intended was present and as definitely and promptly 

 developed as usual. All the other parts of the motor behaviour in the 

 trains of action coming under observation seemed accurate and unimpeded 

 except for the role, as executant, of the particular limb whose motor cortex 

 was injured. And there seemed to be, and to persist for some time, a mental 

 attitude of surprise at the want of fulfilment of that part of an act which 

 had been expected to occur as usual. The surprise seemed to argue 

 unfulfilled expectation, and defect in the motor execution rather than in 

 the mental execution of the act, raising the question whether the function 

 of part of the cortex ablated in such cases be not indeed infra-mental. 



We would not by this suggest that the part of the cortex in which the 

 motor zone is situate may not be involved in processes of synthesis of 

 sensation as well as in that of motor and postural action. The recent 

 experiments by Dusser de Barenne (11), by minutely localised application 

 of strychnine to the cortex of the " motor " zone as well as to other adjoining 

 parts of the cortex, clearly give grounds in support of the view that the 

 cortex of the motor zone influences sensation. 



