156 University of California Puhlications in Anatomy [Vol. 2 



From the above description of the results of the present study of 

 the minute relations of the afferent visual fibers to the various cell and 

 fiber layers of the visual cortex in the brain of the monkey, it is 

 apparent that they stand in all essential points and even in most 

 details in full agreement with those found by means of a different 

 method by Ramon y Cajal in the brain of man. But the present inves- 

 tigations would appear to have further importance in as much as they 

 have, for the first time, clearly demonstrated that in the brain of pri- 

 mates the visual fibers originating from the subcortical nuclei are 

 identical with certain intracortical fiber elements of the striate cortex. 

 The present studies show that a part of the "basal meshwork" in the 

 lower cortical strata ("Grundfaserfilz" of Vogt, 1919, his fig. 34; see 

 also Mauss), especially the stronger fibers in that meshwork which 

 often have an irregular oblique course, are nothing other than incom- 

 ing afferent visual fibers originating in the external geniculate body. 

 (Compare a similar observation on the termination of the somato- 

 sensory thalamo-cortical fibers, Chapter VII.) Thus our work 

 furnishes the final proof for Ramon y Cajal 's opinion of the nature of 

 the coarse exogenous fibers of the striate cortex found and considered 

 by him to be terminations of the afferent visual fibers, a supposition, 

 which although probable, remained until now without definite con- 

 firmation, due to the inability of Golgi 's method to demonstrate long 

 stretches of fibers. The present experiments also show an essentially 

 identical arrangement of the intracortical afferent visual fibers both in 

 higher and in lower mammals (see Ramon y Cajal, 1922 and 1923, and 

 my previous investigations on the termination of afferent visual fibers 

 in the brain of the cat, 1927, fig. 36) . It seems proper to claim for the 

 present experiments, that they have fulfilled the requirement demanded 

 long ago by Monakow (1914, p. 353) as regards the experimental 

 verification of the visual radiation in primates, though the results turn 

 out to be very different from Monakow 's \dew of the extension of the 

 visual projection cortex and of the internal organization of the visual 

 radiation, and, in fact, contrary to most of his views on the organiza- 

 tion and function of the visual apparatus. (See Chapter XVI.) 



