1932] Poliak: Afferent Fiber Systems, Primate Cerebral Cortex 123 



tion is consequently, not quite identical here with that in Experiments 

 II and III, not being a "boundary bundle," though it becomes so 

 more occipitally (fig. 76). This is in accord with the seat of the lesion 

 in the present experiment which is somewhat below the spot of the 

 lesion in Experiments II and III, that is, closer to the "axial" rib of 

 the fiber fan of the visual radiation (represented by M in fig. 13). 



The remaining fibers of the degenerated bundle which do not 

 terminate in the upper lip of the fissura calcarina, proceed occipital- 

 ward, and either ascend dorsally, turning partly around the posterior 

 horn of the lateral ventricle and being gradually distributed to the 

 striate cortex covering the dorsal edge of the occipital operculum on 

 both sides (on the internal and on the external face, fig. 76), or they 

 deviate from the common bundle forming laterally to it the stratum 

 extremum of R. A. Pfeifer, from which they are gradually distributed 

 over the external face of the occipital lobe. In the occipital pole the 

 fibers spread out like a fan supplying a segment of the striate area 

 which lines both lips and the bottom of the ascending branch of the 

 calcarine fissure as far as the limits of the striate cortex (compare 

 lower figure in fig. 12) . Behind this branch of the fissure on the inner 

 face of the hemisphere the supplied segment of the striate area 

 occupies approximately the dorsal half of the occipital pole. On the 

 lateral face of the hemisphere (upper figure in fig. 12) the supplied 

 segment has the shape roughly resembling a triangle, occupying the 

 larger upper portion of the occipital operculum above the external 

 calcarine sulcus. The anterior boundary of this triangle being parallel 

 to the sulcus simialis (Ss) corresponds exactly with the oral boundary 

 of the striate area easily discernible by the presence of the stria 

 Gennari or Vicq d'Azyr (compare fig. 12, with fig. 7, field 17, on the 

 external face of the hemisphere) . 



It was striking to find in this experiment as well as in foregoing 

 ones that no single afferent visual fiber goes beyond the boundary of 

 the striate cortex (fig. 76). It was also true that no degenerated 

 fibers whatever entered any other segment of the striate cortex (lower 

 lip of the calcarine fissure, lower half of the occipital operculum) 

 except the triangle described above. The shaded area along the main 

 horizontal branch of the fissura calcarina (Fcalc in fig. 12) indicates 

 here as in the foregoing experiments merely the longitudinal extent 

 of the supplied zone, the striate cortex being here buried in the fissure. 

 This cortex reaches the free face of the hemisphere only along the 

 ascending and descending branch of the calcarine fissure and, of 



