Johnston, The Radix Mesencephalica Trigeniini. 631 



y and x are seen arising from the nucleus. It should be noticed now 

 that the mesencephalic bundle b-c lies caudo-lateral to the motor 

 nucleus and is distinct from the motor bundles. It will make the 

 •understanding of the following figures more easy if the reader holds 

 in mind that from here on the mesencephalic root is destined to run 

 latero-ventrad and slightly caudad to its point of exit, while the 

 motor root bundles run ventro-cephalad and laterad, so that at this 

 point the bundle b-c shows its nearest approach to the motor bundles. 

 It is this bundle b-c whose separate course has been clearly shown in 

 the transverse sections. The bundle a in this figure is to be found 





■'^^■u-y-fy y^y Vmot-cr 



Fig. 26. The second section of this series ventral to the last, x 20. Descrip- 

 tion in text. 



among the motor bundles, this being the point at which the inter- 

 lacing already described takes place. The fibers will be recognized 

 as a row of short lines set at an angle to the direction of the motor 

 fibers. It is in reality a very thin flat bundle which lies chiefly 

 between the decussating and homolateral motor fibers. This section 

 is the one in which these fibers are most completely intermingled 

 with the motor fibers. To render the relations more clear, I have 

 drawn the same section at a higher magnification so as to be able to 

 show the exact position of the fibers of bundle a more clearly (Fig. 

 27). Every fiber is drawn under the camera with great care. I am 

 unable to find a single fiber of the mesencephalic bundle which seems 

 to turn into the motor bundles. 



