1932] Poliak: Afferent Fiber Syste^n^, Primate Cerebral Cortex 159 



mediate segment of the external geniculate body, which is situated 

 between both internal and external segments of that body. This inter- 

 mediate segment corresponds to both dorsal and ventral quadrants of 

 both homonymous hemimaculae. The vertical branch represents a 

 considerable portion, probably more than half, of the visual radiation. 

 It supplies the striate cortex covering the pole of the occipital lobe, 

 and in the monkey, as far as the striate cortex extends, the external 

 face of the occipital lobe or the so-called operculum occipitale. The 

 vertical branch represents in its upper half, near the dorsal horizontal 

 branch, the upper quadrants of both homonymous hemimaculae ; in its 

 ventral half, near the ventral horizontal branch, the lower quadrants 

 of both homonymous hemimaculae (fig. 22). 



(8) In view of the above statements and the results of pathological 

 and experimental studies of Ronne (1914) and of Brouwer-Zeeman 

 (1926), the following conclusions as to the projection of the retina 

 upon the cortex in primates and in man must be made (fig. 23). 



(a) The upper extramacular quadrants of both homonymous hemi- 

 retinae (lower quadrants of the homonymous halves of the visual fields 

 with exclusion of the macular portion), together with the upper half 

 of the monocular portion of the crossed retina (lower half of the 

 crossed temporal crescent) are projected upon the upper lip of the 

 fissura cal carina (in man, anterior portion of that lip). 



(&) The lower extramacular quadrants of both homonymous hemi- 

 retinae (upper quadrants of the homonymous halves of the visual 

 fields with exclusion of the macular portion), together with the lower 

 half of the monocular portion of the crossed retina (upper half of the 

 crossed temporal crescent) are projected upon the lower lip of the 

 fissura calcarina (in man, anterior portion of that lip). 



(c) The projection zone of the monocular temporal crescent 

 occupies the anterior portion of the calcarine striate area, being its 

 most ''peripheral" zone (in the monkey in both lips). 



(d) Homonymous halves of both maculae luteae and of the fovea 

 centralis are projected upon the pole of the occipital lobe, in the 

 monkey behind the ascending and descending branches of the fissura 

 calcarina, and upon the external face of the occipital lobe, the occipital 

 operculum, as far as the striate cortex extends. The upper half of the 

 polar and the opercular striate cortex represents upper quadrants of 

 both homonymous halves of the maculae (lower homonymous quad- 

 rants of the macular portion of the visual fields) ; the lower polar and 

 opercular half represents the lower quadrants of both homonymous 



