64 THE MEDULLA OBLONGATA AND PONS VAROLI1. 



A large part of the lateral column of the cord, viz., the lateral pyramidal tract, 

 passes into the opposite pyramid of the bulb and proceeds in this and in the 



Fig. 52. DEGENERATIONS IN THE SPINAL CORD, MEDULLA OBLONGATA, PONS TAROLII, AND MESEN- 



CEPHALON OP A MONKEY FOLLOWING HEMISECTION AT THE TWELFTH DORSAL NEKVE. (E.A.S.) 



The hemisection was on the left side of the cord, and was complete. The section outlines drawn to 

 scale with a camera Incida. The degenerated fibres shown by black dots. Those in the section of the 

 lumbar cord are descending, all the rest are ascending, py, pyramidal tract ; d.a-l, descending antero- 

 lateral tract ; d.a.c, dorso-lateral ascending cerebellar tract; d.a'.c' (in Pons III.), degeneration of 

 fibres of this tract in the white matter of the cerebellar worm ; v.a.c, ventrolateral ascending cerebellar 

 tract; v'.a'.c' (in Pons II. and III.), degenerated fibres of this tract passing dorsally into the valve of 

 Vieussens (in Pons III. ) and into the white matter of the vermis (Pons II. ) ; n. III. , n. V., n. VI., n. VII., 

 issuing ribres of the 3rd, 5th, 6th, and 7th nerve-roots ; v.IV., 4th ventricle. 



ventral part of the pons towards the crusta (see fig. 24, p. 30). Together with the 

 small part of the anterior column of the cord which also enters into the constitution 



