64 University of California Puhlications in Anatomy ["Vol. 2 



The posterior Sylvian area alon^ the Sylvian fissure (area x in 

 figs. 2, 10, 24) as found in Experiment II, is completely at odds with 

 the usual delimitation of students of cy to architecture in regard to 

 these regions, for it embraces the ventral part of the parietal area 7 

 and the dorsal portion of the temporal area 22. Yet even this new- 

 receptive area which is probably in close relation to the auditory func- 

 tion has approximately the same position as both of Brodmann's areas 

 mentioned above that stretch alongside the Sjdvian fissure. 



The striking similarity between the shapes of the somato-sensory 

 areas found here and the areas delimited by the students of cortical 

 cytoarchitecture can he explained by the \dew that the structural fea- 

 tures, that is, the cytoarchitectural and my elo architectural peculiari- 

 ties, and to some extent also the myelogenetical characteristics of special 

 cortical territories are the consequence of one and the same cause. They 

 are both the manifest-ations of the functional specialization of each of 

 these areas, which goes hand in hand with the structural changes. 

 These morphological areal modifications of the originally common 

 sensory-motor cortex are, one should assume, the expression of the 

 increase in one area or the reduction in another, or a modification of 

 the previously existing fiber connectio'us, and of the creation of new 

 connections. It is, therefore, apparent, that besides minute cyto- and 

 myeloarchitectural arrangements, fiber connections can also be used, 

 although perhaps with somewhat less exactness, for the delimitation of 

 cortical areas. At least they can be used to- verify the areal delimita- 

 tion found by other methods and thus to corroborate or change the 

 acceptance of certain areas or regions having the significance of func- 

 tional units. Above all, the value of fiber anatomy as contrasted with 

 that of other morphological methods of investigation lies in the fact 

 that it is better qualified to explain the connections of definite cortical 

 areas and consequently their functions, enabling a decision to be made 

 as to whether certain areas must be regarded as receptive or effector 

 centers, or perhaps as intrusted with both these functions. 



It has been already mentioned that neither the boundaries of the 

 common somato-sensory region nor those of individual areas are quite 

 sharp, with perhaps the only exception of area 3. On the whole, the 

 sharpness of the boundaries of the common somato-sensory cortex is 

 not comparable with- the sharp limits of the striate area, determined 

 by cyto- and myeloarchitectural investigations and found in the pre- 

 sent work to be identical with the boundary of the visual projection 

 cortex. (See: Visual System.) Because of its laek of sharp delimita- 



