214 Vniversity of California Pulylications in Anatomy [Vol. 2 



in the visual system ; this knowledge is derived partly from the par- 

 ticularly careful study of the internal org'anization of the visual system 

 in this work. The same principle, however, must not necessarily be 

 considered valid for other afferent systems (olfactory, gustatory), 

 where, in accordance with a different, non-spatial character of their 

 stimuli and impulses, an entirely different architectural and func- 

 tional principle (or principles) migrht conceivably exist. (Compare 

 Ramon y Cajal, 1911; Herrick, 1924; Bornstein, 1928; see following 

 chapter. ) 



Although in view of the results of the present experiments it is 

 necessary to extend the boundaries of the somato-sensory and of the 

 auditory projection cortex beyond the limits determined by the myelo- 

 genetic method of Flechsig and by students of cortical cytoarchitec- 

 ture — though confirming entirely Flechsig's and Henschen's bound- 

 aries of the visual projection cortex by demonstrating its identity with 

 the striate area — nevertheless it appears justifiable to distinguish 

 those cortical regions or areas receiving direct impulses from sub- 

 cortical regions (that is, from the peripheral receptor organs) from 

 other areas and regions for which no afferent fibers were found. In 

 distinguishing between the "projection fields" and the "intercalated 

 or association regions" the qualifications and modifications men- 

 tioned above must, however, be kept in mind. What appears to be the 

 essence of Flechsig's conception, however, seems to be confirmed by 

 the present experiments, namely, that the entire cerebral cortex does 

 not stand in connection with the afferent paths, but that only some 

 cortical areas or regions possess such connections, these areas having 

 a definite location, shape, and extent and a specific function. Through 

 these "gateways" specific impulses from the surrounding external 

 world, as well as from the internal organs of the body, enter the 

 cortical sphere, there to undergo the most varied processes of com- 

 bination and integration. The following question must form the sub- 

 ject of further studies : By what connections are the impulses reach- 

 ing the projection areas distributed to other areas and regions, espe- 

 cially to the intercalated regions, and by what mechanisms are the 

 different impulses integrated into new composite forms of neuro- 

 dynamic phenomena? In other words, how are we to interpret 

 anatomically the function of the projection and association areas, 

 especially that of the temporo-parietal and frontal regions? 



At any rate, the present experiments corroborate the belief in an 

 unequal, diversified representation of various functions in different 



