ARCHITECTURE. 195 



and ventral portions are exhibited by a diagram like the 

 following, 1 in which the shaded portion represents the 

 part that has been derived from the ventral plates, while 

 the unshaded portion represents that derived from the 

 dorsal plates. 



Examining the encephalon as thus divided, we find 

 that the cerebellum, the dorsal portions of the 



FlG. 35. Schema showing the encephalon and cord. The 

 unshaded portion is that derived from the dorsal plate, 

 and the shaded that from the ventral. (From Minot.) 

 C, cerebrum ; Cb., cerebellum ; F., foramen of Monro ; 

 /., infundibulum ; 3/., bulb ; O., olfactory lobe ; / J ., pons; 

 Q., quadrigemina ; Sp.c., spinal cord ; ///., third ven- 

 tricle ; IV.) fourth ventricle. 



quadrigemina and thalamic ganglia, as well as the 

 entire mass of the cerebral hemispheres, are derived 

 from the dorsal plates. These parts of the encephalon 

 are therefore the homologues of the dorsal horns of the 

 spinal cord. This portion of the cord is occupied by 

 1 Minot, Pop. Science Monthly, 1893. 



