200 University of California Puhlications in Anatomy [Vol. 2 



posterior horn of the lateral ventricle and (4) the cortex of the 

 fissura calcarina with its subcortical fiber layer (calcar avis). 



The visual radiation terminates exclusively in the area striata of 

 Elliot Smith, field 17 of Brodmann or the area OC of Economo- 

 Koskinas (shaded areas in fig'. 21 ; see also fig. 24 and compare with, 

 fig. 7). No other portion of the cortex of the parieto-occipital lobes, 

 not even the narrow strip of cortex surrounding the striate area and 

 called "limes parastriatus gigantopyramidalis" (Economo-Koskinas), 

 receives any afferent visual or any other afferent fibers in the brain of 

 the monkey. The limits of the cortex receiving the afferent visual 

 fibers and the boundaries of the striate area discernible by the pres- 

 ence of the stria Gennari or Vicq d'Azyr are everywhere identical. 

 This was especially striking in sections showing portions of the striate 

 cortex (marked with number 17 in fig. 76) alternating with portions 

 of the parastriate area, Brodmann 's area 18 (marked with number 

 18 in the same figure). Here the degenerated visual fibers enter only 

 those portions of cortex where the stria Gennari or Vicq d'Azyr is 

 visible, leaving other portions of the cortex entirely free. When still 

 in the subcortical white substance the degenerated fiber bundles keep 

 close along the striate cortex, completely avoiding the other half of 

 the white matter which is close to the non-striate cortex, in a manner 

 similar to that described for the auditory radiation (compare Audi- 

 tory System). 



Taken together, all this means that the visual radiation has a single 

 subcortical origin (external geniculate body) and a single cortical 

 terminal area (area striata) ; hence in particular the hypothesis of a 

 threefold or a multiple cortical projection of the retina perhaps at 

 spots widely distant and outside the striate area (Dejerine, Monakow, 

 Goldstein, et al.) has no anatomical foundation. 



The striate area is uniformly supplied with afferent fibers and, 

 accordingly, no special "nuclear or focal zone" comparable to that 

 of the somatic sensory and the auditory cortical projection areas was 

 found. Neither were any small, richly supplied islets of the striate 

 cortex found, separated from each other by narrow zones devoid of 

 afferent visual fibers. Possibly the supply of the macular cortex is 

 somewhat more abundant than that of the perimacular cortex. 



In the striate cortex itself the fairly coarse exogenous afferent 

 visual fibers have a more or less oblique course, are mostly distinct 

 from the actual "radiary" bundles, and ascend upward as far as the 

 stria Gennari or Vicq d'Azyr (fig. 65). They must, therefore, be 



