i66 jouKNAL OK Comparative Neuuolo(;y. 



tinuation of the cell cluster which envelops the olfactory. 

 The centre of the nidulus is tilled with non-medullated fibres 

 and a few small cells. The cortical portion is composed of 

 densely clustered fusiform cells with round, clear nuclei. 

 These cells are less than half the size of those which occupy 

 the centre of the lateral portions. The lateral and ventral 

 part of the basal portion is occupied by a broad band of 

 neuroglia, with numerous non-medulated fibres passing 

 apparently toward the anterior commissure. 



The lateral portion of the hemispheres' consists of a more 

 or less quadrangular segment, bordered dorsad and mesad by 

 the ventricle: laterad it forms the wall of the brain, and 

 ventrad it is in direct contact with the basal portion just 

 described. From this portion it is separated laterad by a fibre 

 tract which, in transverse section arches ventrad from the 

 lateral surface to the nidulus of the basal portion. Ventrad 

 to it and apparently associated with it is the system of con- 

 centric fibres, already described upon the periphery of the 

 basal portion. Dorsad, this tract may be traced along the 

 entire lateral periphery of the lateral lobe. Immediately 

 dorsad and mesad from the tract there are a number of small, 

 dark pyramidal cells, with their long axes toward the peri- 

 phery. Similar cells are crowded at the dorso-lateral angles. 

 The entire dorsal and mesal portion of this part of the 

 cerebrum is filled with from six to ten irregularly concentric 

 series of fusiform cells. These are of moderate size, and are 

 characterized by the circular, clear and granular nuclei, and 

 by the pale protoplasm of the body, which varies greatly. 

 Often the form is flask-shaped, with one strong process 

 peripherad, and several from the blunt end extending toward 

 the ventricle. Along the median portion of the ventricle the 

 number of rows is reduced, and the character of the cells 

 changes. Here the cells are much larger and more multipolar 

 in form, still preserving the same general character otherwise. 

 It is obvious that it is this region which proliferates the 

 large aesthesodic cells of the central portion of this region 



