FASCICULUS CEREBRO-SPINALIS IN THE RAT 



415 



and in that the decussation in the rat is complete. No pyramidal 

 fibers run directly down on the same side into the anterior funicu- 

 lus of the cord. 



In the cervical region of the spinal cord (fig. 4, c. 7) these tracts 

 occupy the ventral portion of the posterior funiculi and are closely 



Fig. 3 Medulla oblongata, lower end of the decussation of the pyramids; a, 

 lowest decussating fibers. Ocu. 0, Obj. 3. 



Fig. 4 Seventh cervical segment of the spinal cord. Ocu. 0, Obj. 3. 



approximated to each other and to the curved surface of the 

 culumna posterior. Since the medial and posterior surfaces of 

 of the bundle are almost at right angles to each other, the shape 

 of the tract, as seen in sections through this level of the cord, is 

 that of one-fourth of a circle. There is not as much intermingUng 



