43 



The region of the brain through which the fibers pass is a thickened 

 portion of the lamina terminalis. Sections made in the horizontal 

 plane (Fig. 8) show that, deep within the median furrow, the roots of 

 the nerve, on each side, penetrate the mesial surface of the pros- 

 encephalon. After entering the brain they pass backward, dividing into 

 two or three branches, which in turn are greatly subdivided. Their 

 branches become more numerous, finer and wider spread the deeper 



Fig. 7. Another section of the same embryo as Fig. 6. Minot collection, No. 426, 

 sec. 281. Shows both roots on the surface, but only the ventral one within. ^ oc. 2, 

 obj. -/a in. 



they penetrate into the brain substance, and, near the wall of the 

 ventricles, they are numerous and finely divided. The distribution of 

 the nerve fibers is confined mainly to the side they first enter, but, 

 as shown in the diagram, a relatively large branch from each side 

 crosses the middle plane and divides into a number of twig-like 

 terminations, which intermingle with the terminal branches of the 

 opposite side. 



The exact nature of their internal cellular connections has not 

 yet been made out satisfactorily. I have found, however, in embryos 



