626 'Journal of Comparative Neurology and Psychology. 



The motor nucleus is indicated in Fig. 21 by a dotted line and in 

 Fig. 22 by the line along which the section was broken. Its dorso- 

 lateral surface is covered, as in the younger specimen, by bundles of 

 the motor root. On each side there is a broad but loose bundle of 

 decussating fibers and beneath this are denser bundles of fibers arising 



Vmes. I 'flj V, 



V mot nac 



'/ V sens 



Fifi. 22. Same specimen as in Fig. 21, two sections fartlier caudal on the 

 right side, x 20. 



from the motor nucleus of the same side. The motor bundles run 

 ventro-cephalad and are cut obliquely in the section a short distance 

 ventral to the lower border of the motor nucleus. 



The mesencephalic root of both sides is clearly formed of fibers 

 from the sensory root and only obliquely crosses the motor bundles 



