DEGENERATIONS IN THE SPINAL CORD. 



If the section of the cord is confined to one lateral half the tracts of degeneration 

 are limited to the side of the hemisectiou, but a few degenerated fibres are seen in 

 the corresponding tracts upon the other side above the hemisection (fig. 27). 



Medulla. oTrlonc/ata 



d.a.c. 



Fig. 27. DEGENERATIONS IN THE SPINAL CORD, MEDULLA OBLONGATA, PONS VAROLII AND MESEN- 



CEPHALON OP A MONKEY, FOLLOWING HEMISECTION AT THE 12TH DORSAL NERVE. (E.A.S.) 



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

 scale with a camera lucida. 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. , ventro-lateral ascending cere- 

 bellar tract (Gower's 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 (in Pons II. ) ; 

 n.III., n.V., n.VL, n.VJI., issuing fibres of the 3rd, 5th, 6th, and 7th nerve-roots; v.IV. , 4th 

 ventricle. 



Nearly all the degeneration is on the same side as the lesion. A few fibres are degenerated on the 

 opposite side (perhaps from a slight accidental injury of that side of the cord). 



VOL. III. D 



