1932] Poliak: Afferent Fiber Systems, Primate Cerebral Cortex 143 



segment of the lateral g-eniculate body would send a part of its fibers 

 to the opposite striate area this would in our experiments have most 

 probably resulted in a "blurring" or in a complete obliteration of 

 the "figures" of the degenerated zones in both lateral geniculate 

 bodies. 



Experiment V-d 



The purpose of this and of the following experiment (V-e) was to 

 destroy as completely as possible the striate area of the one oecipital 

 lobe, and in this way, produce the "primary irritation" or "retro- 

 grade degeneration" of all cells whose fibers terminate in the 

 removed portions of the cortex (Nissl). Here the chief interest was 

 concentrated upon the questions: (a) Do all nerve cells of the ipsilat- 

 eral external geniculate body degenerate, or only some of them? (b) 

 Do any of the nerve cells of the opposite .external geniculate body 

 degenerate ? It was obvious that if all cells of the external geniculate 

 body send their axis cylinders to the striate area of the same side, and 

 consequently none of the fibers of the visual radiation terminate in the 

 pulvinar, in the tectum, or in the striate area of the opposite side 

 ("fasciculus arcuatus corporis geniculati lateralis" of Ferraro, "fas- 

 ciculus corporis callosi cruciatus" of Niessl von Mayendorf and of 

 R. A. Pfeifer), and if there are no intercalated cells in the external 

 geniculate body, as it was supposed ("Schaltzellen" of Monakow), a 

 complete degeneration of nerve cells of that nucleus ipsilateral with 

 the destroyed striate area was to be expected. It was equally clear 

 that if some of the fibers of the visual radiation terminate in the oppo- 

 site occipital lobe, this would be manifest by a partial degeneration 

 of the cells of the external geniculate body opposite to the destroyed 

 striate area. 



In a young Java nionlcey the left occipital lobe was completely 

 removed by means of a thermocautery. Twenty-four days later the 

 animal was killed. No open wound of the skin, no pus or inflammation 

 under the skin or beneath the bone flap was found. The left occipital 

 lobe was found to be entirely absent (fig. 19) ; the dura was slightly 

 adhering to the surface of the defect and under the dura covering the 

 defect a small quantity of a milky fluid was found (probably the cere- 

 brospinal fluid mixed with the detritus of the disintegrated nerA'ous 

 substance). Macroscopically and microscopically the entire striate 

 area of the left occipital operculum and that of the posterior half of 

 the calcarine fissure was absent, but the anterior half of the fissure — 



