1932] Poliak: Afferent Fiber Systems, Primate Cerebral Coi'tex 137 



shape, ete, between the piece of banana and the details of the hand 

 were too slig'ht for the food to be correctly seen, or recognized, or 

 localized. The whiteness of the hand and of the piece of food merged 

 into one single "figure," and because the hand represented a larger 

 part of the ' ' figure ' ' there was a greater chance that he would touch 

 the hand rather than the food. Nevertheless, sometimes after from five 

 to ten attempts he aimed better and reached directly for the food. This 

 rather indicated a simple disturbance of the visual perception, of 

 localization and fixation, since the understanding of the "meaning" 

 of food ("something to eat") was evidently only retarded but not 

 essentially impaired. The process of recognizing and identifying 

 appeared to be distinctly slowed down. The protective eye reflexes 

 were not always present, especially after prolonged exercise, but they 

 could almost always be evoked after a pause. They were present on 

 both sides. A difference in the size of the pupils was not noticed. The 

 change in "character" of this monkey was always the same: while 

 the normal Macacus rhesus follows all changes in his surrounding 

 with complete distrust and almost invariably reacts with fear and 

 flight, our monkey became ' ' docile, ' ' did not run away, and regularly 

 took the food from the hand. It is entirely conjectural whether this 

 change was due to the defect in simple perceptive visual processes 

 because of the incompleteness of his \'isual impressions, or was due 

 rather to the disturbance of higher cognitive and similar functions. 

 (The latter assumption would seem more probable since the monkey 

 could very well recognize various sounds, especially "signals of dan- 

 ger" emitted by his ever watching companions). 



As is clear from the foregoing description there were in the pres- 

 ent experiment manifest signs of a right homonymous hemianopsia 

 which was probably due to the more extensive damage to the left 

 macular cortex, besides other symptoms due to the fact that the right 

 macular cortex was also damaged. 



Twenty-three days after the operation the animal was killed. The 

 study of the left occipital lobe, stained according to Nissl's method, 

 revealed three small injuries and a large one of the occipital oper- 

 culum (fig. 17). The injury (&) is almost purely cortical and is 

 sharply delimited; the injury (c) is also well circumscribed though it 

 penetrates slightly into the subjacent white matter and interrupts 

 there a small bundle of the afferent visual fibers ; because of the 

 arrangement of these fibers in the sagittal direction at the point of 

 their interruption, it was assumed that though the segment of the 



