632 Journal of Comparative Neurology and Psychology. 



Above and below the section just described the relations of bundle 

 a are entirely clear. Proceeding with the series, Fig. 28 ^3hows the 

 full extent of the motor nucleus and all of the motor bundles formed. 

 The nucleus is pear-shaped with the small end caudad. A few decus- 

 sating motor fibers are seen passing over this small part of the 

 nucleus to join the bundle z which receives also fibers from this part 

 of the nucleus. The bundle ij is also a mixed bundle of decussating 

 and homolateral fibers. From the large cephalic part of the nucleus 

 are being formed the remaining motor bundles which are marked 



Vmot riuc \ 



^mot cr 



Fig. 27. Same as in Fig. 2G. x '^^- Description in text. 



V, w and x. Between the bundles x and y are seen the curving fibers 

 of the bundle a of the mesencephalic root, just extricating themselves 

 from the motor bundle x. Lateral to the bundle a are seen the fibers 

 of the bundle h-c, now loosely scattered. The letters a, h and c stand 

 at the angles of a triangle which includes the fibers of the mesen- 

 cephalic root and nearly all the fibers appearing within this triangle 

 belong to that root. All these fibers are clearly traced in the inter- 

 mediate sections. It is probable in this and the following sections 

 that a few of the fibers in the a-h-c area end in the sensory nucleus, 



