14 Journal of Comparative Neurology. 



dividing to mingle with the previously described fibres. The basi-lat- 

 eral processes (there are no axial basal processes in the sense implied 

 by Meynert) subdivide and form a diffuse mesh-work or felting which 

 is nowhere concentrated to form a definite zone. Although it cannot 

 be considered certain, it nevertheless seems probable from the appear- 

 ance of the sections that these processes become associated indirectly 

 with the cells next to be described. 



The median and deeper parts of the cortex are everywhere, ex- 

 cept in a few isolated motor nests, sprinkled with cells of a very differ- 

 ent appearance. The cell-body scarcely stains with mercuric hem 

 atoxylin but the nucleus is brought out distinctly without being rend- 

 ered opaque. The latier is large, often quite as large as the diameter 

 of the smaller pyramidal cells. The contents of the nucleus are gran- 

 ular. The area about the nucleus may be vacuolate or the somewhat 

 shrunken fusiform or irregular cell body may be sufficiently stained to 

 be detected with care. 



In a great many cases it is possible to trace the basilateral process- 

 es of the large pyramids to the immediate vicinity of these cells where 

 they seem to form a loose reticulum. 



The pyramids almost uniformly have near their bases one or more 

 small dark nuclei such as we have called Deiter's bodies. The regions 

 of the cortex near the white fibre zones are filled with multipolar cells 

 with several basal and one peripheral process as the rule. 



Histology of the ventral part of cerebrum. Fig. i, Plate B illustrates 

 the appearance of a horizontal section taken ventrad of the union of 

 thalamus and hemisphere. Three distinct portions are presented; 

 cephalad the large olfactory lobe with quadrangular outline and large 

 ventricle. The pero is evidently separated from the pes by a gangli- 

 onic layer. The lobe obliquely applied to its crus so that the median 

 surface extends much farther caudad than the lateral. The radix lat- 

 eralis appears as a thick tract passing directly caudad to the pyriform 

 lobe. The crura are long and connect with the ventro-median pro- 

 jections which we have called post-rhinal {or ventro-median) lobe. 

 (The olfactory region is described in detail above. 



The post-rhinal lobe is largely covered superficially by olfactory 

 fibres. Entad to this are irregular clustres Of cells and dense aggre- 

 gates of Deiter corpuscles in opaque patches of neuroglia. The cells 

 are of the type which we have termed rhino-morphic, i. e. are small 

 irregular pyramids. Fig. lo, Plate A illustrates such cells upon the 



