1932] Poliak: Afferent Fiber Systems, Primate Cerehral Cortex 111 



the striate cortex, supplied by compact bundles, receives everywhere 

 numerous afferent fibers. There do not exist, accordingly, any small 

 portions of the visual cortex without an adequate afferent fiber supply, 

 or any gaps in that supply, so far as can be determined by the method 

 applied here. (Compare identical observation with regard to the 

 supply of the somatic sensory cortex around the sulcus centralis. 

 Chapter VII.) Where the compact degenerated bundles enter the 

 cortex their fibers tend toward it in a uniformly arranged stream. 

 Attention must also be called to the particularly dense fiber supply of 

 the external, opercular portion of the striate area, especially around 

 the shallow sulcus calcarinus externus (sulcus occipitalis superior), 

 and of the entire occipital pole (for explanation see Chapter XVI 

 and XVII). 



The further observation is that all afferent visual fibers, degen- 

 erated in this experiment, enter the striate area exclusively. It is 

 striking to see how strictly these fibers observe the limits of the striate 

 cortex. When still in the subcortical white substance the fibers keep 

 close to that side where the stria of Gennari or Vicq d 'Azyr is visible, 

 leaving the remaining portion of the white substance free (lower part 

 of figs. 40-42 ; a similar feature was obserA^ed in all four remaining 

 experiments; see figs. 13, 56, 57, 72-76). On sections where both the 

 striate and peri-parastriate cortex appear, degenerated afferent visual 

 fibers enter exclusively that portion of the cortex which contains the 

 stria Gennari corresponding with Brodmann's area 17. The boundary 

 between the cortex receiving afferent visual fibers and the remaining 

 cortex is in all sections as sharps as the limits of the stria Gennari or 

 Vicq d'Azyr and is, in fact, identical with the latter (dotted stripe in 

 the lateral portion of the striate area, right lower comer in figs. 40-43 ) . 



As to the extent of the visual cortex receiving afferent fibers in this 

 experiment the following can be said : On the external face of the 

 hemisphere the supplied portion of the cortex includes the entire 

 striate area occupying almost the whole occipital operculum (shaded 

 area in fig. 1, upper figure, compare with fig. 7, field 17). The 

 boundaries of the supplied cortical area and those of the striate area 

 or field 17 of Brodmann, are exactly congruent, as already mentioned. 

 Other areas, fields 18 and 19 of Brodmann, surrounding the striate 

 area (in front and behind the sulcus simialis 8s) remain entirely free 

 of any degenerated fibers. On the medial face of the hemisphere the 

 area striata also receives cortico-petal visual fibers although not in its 

 entire extent (fig. 1, lower figure) . Here the supplied segment includes 



