136 University of California Publications in Anatomy \yoi^. 2 



retired to his comer of the cag'e. (The monkey was in a poor condi- 

 tion during the first five days because of erysipelas of the face.) 

 Three days later the signs of hemianopsia on the rig-ht side were again 

 apparent. The monkey appeared to be unable to understand the mean- 

 ing of threats, not reacting to these with either the movements of the 

 eyes or of the head, or with attempts to escape, as do normal animals. 

 Had it not been known that his \dsual cortex on both sides was dam- 

 aged one would have regarded his disturbance as the visual agnosia. 

 On the next day the same symptoms were again apparent; mainly 

 hemianopsia to the right and quasi-agnostic visual disturbances. When 

 a piece of banana was offered to him he reached for it as soon as he 

 noticed it (after a while) but usually missed it, touching or grasping 

 the fingers of the hand offering food; and only gradually by "touch" 

 did he find the food. From this observation one gets the impression 

 that the monk:ey had a distinctive defect of the visual localization 

 due to the lesion of that portion of the visual cortex which represents 

 points of fixation, besides other perceptive disturbances due to mul- 

 tiple scotomata. There was also a change in the character of this 

 animal : he had lost the fear which characterizes most monkeys, who, 

 as a rule, immediately become vigilant and try to escape into the 

 most distant comer of the cage as soon as one enters the room or 

 approaches the cage, or even makes an unexpected move. Three days 

 after that homonymous hemianopsia on the right side was again 

 present, though this seemed to be incomplete. At any rate, the monkey 

 ignored the objects appearing on his right side, while as soon as they 

 appeared on his left side he reached for them. When reaching for the 

 food he exclusively used his left hand, that is the hand ipsilateral 

 with the halves of his \isual fields still functioning fairly well. In 

 contrast to that he used his right hand quite well in such acts where 

 the visual control was not required to a great degree, or when it was 

 required in a more summary waj^, as for example in slow climbing, 

 in scratching the fur, and the like. When grasping for the food the 

 monkey made the same error as before : he reached too far as a rule, 

 at the same time he usually missed the object to his left. He likewise 

 exhibited the same disturbance in fixing (seeing, recognizing, identi- 

 fying 1) the pieces of food : when one held a piece of banana toward 

 him he at first touched the hand or tried to grasp the fingers, and 

 then, only by slowly feeling and searching the hand did he find the 

 banana. This was thought to be due to the fact that because of 

 the numerous gaps in his visual fields, the differences in color and 



