402 



THE BKAItf OF MAMMALS, BY TH. MEYNERT. 



mates), so that it is only in Man that the hemispheres are exclusively 

 connected by the corpus callosum and the anterior commissure. 



This cortical substance gives origin to the whole of the 

 white substance of the cerebral hemispheres. Not even a 

 remote approximation has yet been made to a perfect repre- 

 sentation of this connection, in transparent sections of the 

 brain. The absolute knowledge that we at present possess 

 upon this point may be comprised in the following remarks : 



The medullary systems of white fibres that may in general be 

 distinguished, have already been mentioned in the introduction 



Fig. 240. 



Fig. 240. A glomerulus olfactorius of Man. N t The entering olfac- 

 tory nerve ; 6r, vessels. Magnified 600 diameters. 



to this chapter. They are (1) the fibrae arcuatae, or connecting 

 systems ; (2) the callosal system ; (3) the fasciculi which pass 

 into the medulla of the cerebellum ; (4) the projection systems ; 

 and (5) the anterior commissure. 



In fig. 233, the letters pr point to an example of the gar- 

 land-like interweaving of two adjoining convolutions, by means 

 of librae propriae which surround the sulcus between them. 

 The letters arc represent fasciculi that run parallel to the 

 longitudinal axis of the hemisphere, from its occipital to its 



