FASCICULUS CEREBRO-SPINALIS IN THE RAT 



417 



out laterally is more pronounced. In the lower lumbar segments 

 (fig. 7, L. 5) the fibers are diffusely scattered through the ventral 

 part of the posterior funiculus and the tract has lost entirely its 

 definite outline. 



Fig. 6 Twelfth thoracic segment of the spinal cord. Ocu. 0, Obj. 3. 

 Fig. 7 Fifth lumbar segment of the spinal cord. Ocu. 0, Obj. 3. 



There is a progressive decrease in the size of the pyramidal 

 tract as it runs caudad through the posterior funiculus of the 

 spinal cord. This is seen on comparing the seventh cervical 

 (fig. 4) with the twelfth thoracic segment (fig. 6). 



