"JO JorUNAl, OF COMI'AKATIXE NeI' I{()1,C)(;Y. 



Structure. — This lobe consists of the following parts: 



I. A narrow outer layer of free cortex. 



3. A broader inner collection of nerve cells, among 

 which is scattered a large number of Deiter's corpuscles. 

 This is the frontal i/iduh^s. These cells are pyramidal in 

 outline and have convex or straight sides. They are from 12 

 to 16 micro-millimetres long and at the base are about six 

 micro-millimetres wide. The apex is extended into a long 

 process, while the base is supplied with several shorter 

 processes. These cells stain densely and have a dense 

 nucleus and a denser nucleolus. (Plate VIII, Fig. 4.) 



AXIAL REGION. 



The axial region is composed of two parts, the basi- 

 occipital lobe and the corpus striatum. 



Basi-occi pital Lobe. — As has been mentioned above, the 

 lateral division of each hemisphere is surrounded on the 

 ventral, mesa! and dorsal sides by the lateral ventricle. In 

 the ventral part of tliis portion of the brain lies the 

 basi-occipital lobe. The caudad and part of the mesal boun- 

 dary of this lobe is formed by the parietooccipital lobe. 

 The ental and dorsal boundaries are formed by the corpus 

 striatum. 



Structure. — This lobe is composed of numerous Deiter's 

 corpuscles, among which are distributed many fusiform 

 or flask cells. These cells are about six micro-millimetres 

 wide and from \i to 16 micro-millimeties long. They stain 

 faintly and contain a large, clear, subspherical nucleus and a 

 dense nucleolus. In all probability these cells are undergo- 

 ing rapid transverse subdivision (Plate VIII, Fig. u). In 

 the reptilian brain also, according to Prof. Herrick, the cells 

 of this lobe are undergoing rapid subdivision. In that case, 

 however, the subdivision is radial.('j 



I See •■ Notes on the Brain of the Alligator," by Prof. C. L. Herrick, Jonrnal of 

 Cinr innati Society of Natural History, Vol. XII, Plate VII, Kis. K. 



