186 Ley ton and Sherrington 



widely and liberally through the ventral horn. Our sections have not 

 detected changes in the perikarya of the motoneurons, even where the 

 minute nerve-fibre degeneration is most heavy. 



Ablation-Experiment 2. Removal of part of the Arm Area 

 from both Hemispheres (fig. 5, A, B, C, and fig. 22). 



Troglodytes niger, $ , ol Kola-kaamba type; arrived at laboratory 

 from W. Africa, March 26, in rather cramped cage, but perfectly healthy. 

 Transferred to roomy laboratory quarters, and allowed in and out of his 

 new quarters. Habits observed ; after eating, picks teeth with nail of 

 extended index finger, usually of left hand, but no clear preference in use 

 of left hand over right, employing right and left seemingly equally, except 

 for doubtful preference of left in picking teeth. Accepts fruit (bananas, 

 apples) with either hand ; often stores the fruit so taken. Another chim- 

 panzee, $ , in the same quarters, was at once treated as a friend ; on receiv- 

 ing biscuit, Paddy, who did not care much for biscuit, gave most of it at 

 once to his " girl friend," handing it to her. Occasionally he was seen to kiss 

 her, perhaps a trick learned on voyage. Not rarely walked fairly erect with- 

 out touching floor with fore-limbs at all, especially when free in the room 

 outside the case, but sometimes in the cage. When wantiiior to attract 

 attention, or vexed at not getting his own wa}^ stamps one foot or both 

 feet on the floor. Makes a considerable variety of sounds, especially a 

 sucking noise, with lips protruded. Sleeps with one arm under head for 

 pillow, lying on side. Dungs in one corner of his cage. 



1st Operation, January 3. — Has been in laboratory more than nine 

 months. Chloroform and ether mixture (equal parts) administered, and 

 taken very well ; loud snoring when under deep narcosis. Trephined on left 

 side ; the hand area of left cerebral hemisphere exposed through the suitably 

 enlarged trephine hole. Dura mater turned back in flaps ; arachnoid care- 

 fully opened, allowing much subarachnoid fluid to escape. 



The exposed convolutions thus freed from fluid were stimulated. Uni- 

 polar faradism was used for the most part, with occasional application of 

 the ordinary double-point electrodes. Temperature of room 29° C. through- 

 out experiment ; temperature in rectum 37'4° C. at commencement and 

 37° C. at end of operation. Ether narcosis maintained throughout. 



The cortical region exposed included the precentral and post-central 

 convolutions above and below the inferior genu of central fissure. The 

 post-central was carefully explored by faradisation with both forms of 

 electrodes, and with the same strength of stimulus as was employed for the 

 precentral, but no movement was at any time elicited by the stimulations, 

 although the similar stimuli applied to the precentral evoked movements 

 regularly. The whole vertical length of precentralis, as far as it was laid 

 bare, was found excitable, but the anterior portion of its horizontal width 

 did not respond with such certainty as did the rest. The exact topography 



