The Excitable Cortex of the Chimpanzee, Oraii;,'-Utan, and (iorilla 181 



thiin at elbow. It moves right fingers little, and thumb and index hardly 

 at all. There is a frecjuent twitching adduction of right thumb. Animal 

 seems unable to grasp with right hand; tlie right hand slips on the 

 vertical bars of the cage wlien animal tries to hold them l»y it. 



March 27, — The movement of right shoulder is obviouslv defective. 

 The condition of right hand and elbow is the same as yesterday ; but the 

 animal rarely now attempts to use the hand for grasping, etc. ; it seems to 

 have learnt its disability in regard to that hand, and to do without it. 

 Animal seems very well otherwise, and is active. Wound looks well. 



^larch 30. — The movement of right shoulder lias improved, but other- 

 wise the condition of right arm remains apparently the same as on the day 

 after operation. The animal was seen sleeping with its head pillowed on 

 right arm, as was not unusual with it before the operation. 



oLyi^x'isV w^>i^ 



I cm 



Fig. 19. — Map showing the cortex area ablated in ablation-experiment 1. 

 The numerals indicate the responses obtained from it and its neighbour- 

 hood. Dotted lines indicate the edges of the ablation, the top one that 

 of May 3, the others those of JIarch 26. The numerals refer to the 

 "list of motor responses," pp. 148-154. denotes that at no time did 

 stimulation of the point so marked evoke any response. 



April 26. — Right shoulder seems perfect in all movements, so also 

 elbow. Animal often supports itself in the quadrupedal posture by one 

 fore-lirnb, while the other is used for feeding, etc. ; for such support the 

 right arm is employed seemingly as often as the left, the hand resting on 

 the knuckles, and the support involving fixation of elbow in extension and 

 of somewhat protracted shoulder. Wrist is moved well, and if any wrist- 

 drop is present it is slight, although that wrist is often postured in a some- 

 what drooping pose, but questionably more so than usual. The three 

 ulnar fingers seem perfectly strong and good in all actions. Index is 

 imperfectly moved ; it is generally flexed along with flexion of the ulnar 

 three finorers, but without much strength. Nor does it follow the flexion 

 of the ulnar three digits perfectly, for occasionally when the vertical bars 

 of the cage are grasped by this hand the ulnar three fingers clasp the 

 bar, but the index, although incurved, is curved not round the bar, but 

 between the bar and the palm. This does not happen with the sound 

 left hand. Neither is index of riorht hand ever seen to be moved in- 

 dependently of the other digits, although that is frequently the case in the 



