'Wiiw.H. A/or/)/M)/oj^>v of the Avian Jyraii/. 73 



3. An undulating line, which passes, in general, dorso- 

 caudad from the dorsal extremity of curve two to the dorsal 

 extremity of this division.. The ventral half of this curve is 

 strongly concave, while the dorsal half is strongly convex. 



Viewed from above, the outline of this division is com- 

 posed of the following curves: 



1. A convex curve, which extends cephalo-laterad from 

 the mesal extremity of this division to the cephalo-mesal 

 border of the same. This curve is formed by the ventricle. 



2. An undulating line, which passes latero-cephalad from 

 the extremity of curve one to the latei'o-cephalad border of 

 this division. At its extremities this lobe is feebly convex, 

 in the middle it is feeble concave. 



3. A convex curve, parallel to the lateral surface of the 

 hemisphere, which extends from the extremity of curve two 

 to the caudo-lateral margin of this division. 



4. An undulating line, which extends, approximately, 

 mesad from this place to the beginning of curve one. The 

 lateral one-tenth of this curve is slightly concave, the suc- 

 ceeding four-tenths is moderately convex, the next four- 

 tenths is strongly concave, and the remaining one-tenth is 

 almost straight. 



Cell structure. — Histologically, this division of the stria- 

 tum differs from all other parts of the brain. Some of the 

 cells are fusiform, while others are sub-pyramidal; but the 

 greater number are swollen and distorted and contain several 

 nuclei (Plate VIII, Fig. 10). The numerous small cells, 

 resembliiig Deiter's corpuscles, that are present in this part 

 of the striatum are of the same size as the nuclei of the large 

 cells. No other portion of the prosencephalon is so well 

 supplied with blood-vessels. This suggests that this is an 

 area of great activity. Evidently it has a special work to 

 perform. Professor Herrick suggests that it may be an area 

 where germinative corpuscles are produced. 



The corpuscles of this region resemble Deiter's corpuscles 

 in so many respects that one is tempted to believe that they 



