146 TEIJI HOSHINO 



8.6 n in the normal; the staining properties of the fibers here 

 are poor. 



The fiber groups which go dorsally and to the ventral portion 

 of the acoustic area and which pass into the ventral part of the 

 nucleus parvo-cellularis are slightly smaller than normal. In the 

 ventral region of the cerebellar peduncle, between the medial 

 edge of the spinocerebellar tract and the lateral region of the 

 'Bogenzug,' we find an area of large ganglion cells which is the 

 proximal process of the nucleus magno-cellularis. The trans- 

 verse breadth of this nucleus here measures 0.835 mm. in the 

 affected and 1.084 mm. in the normal; its dorso ventral boundary 

 is somewhat difficult to make out because of the close relation 

 to the ventral cells of the nucleus cerebellaris lateralis. The cere- 

 bellar peduncle has a small breadth and the lateral fiber mass in 

 this peduncle which is composed of fibers that come mainly 

 from the medulla oblongata has a breadth of 0.334 mm. in the 

 affected and 0.835 mm. in the normal, or a ratio, therefore, of 

 1:2.5. 



The difference of the external ventral arcuate fibers between 

 the normal and affected becomes more prominent than ever at 

 this point, 0.100 mm. in normal and 0.066 mm. in the affected 

 birds. The staining properties, caliber, and other conditions of 

 each individual fiber are the same as described before. It is 

 clearly seen that the librae arcuatae externae ventrales run latero- 

 dorsally and enter the restiform body and with the tractus spino- 

 cerebellars pass dorsally up to the lateral edge of the cerebellar 

 peduncle. The fibers in the reticular formation have the same 

 changes as noted at the former level. The changes in the fasc. 

 long, med., the external ventral arcuate fibers, the lateral portion 

 in the cerebellar process, and the restiform body are the main 

 important differences in the affected pigeons at this level with, 

 however, no apparent degenerative processes in either fibers or 

 nuclei. 



The facial nerve and its nucleus appear normal. 



The level of the sensory trigeminal nucleus. The spinal root of 

 the trigeminal nerve is pierced ventrodorsally by a few fibers 

 which come from the reticular formation and pass toward the 



