SPINAL CORD REGENERATION. II 433 
Where the continuity of the cord was restored by either active 
or per primum healing, this cavity opens into the canalis cen- 
tralis of the caudal end of the cord. The original, rather wide 
funnel-shaped cut edge of the ventricle has been rounded over, 
chiefly by the curling downward of the very thin dorsal wall, a 
portion of the inferior medullary velum. Where the part of the 
medullary ventricle reversed was considerable, the rounding- 
Fig 4 Frontal section through a portion of an embryo, the spinal cord of 
which was reversed. At the left hand side of the figure the remnant of the 
medullary ventricle is visible and in the middle of the figure the slight uneven- 
ness of the central canal marks the point of fusion of the cephalic cut. It will 
be noted that the walls of the medullary ventricle have become narrowed. 
Fig 5 Graphic reconstruction of the central nervous system of the same 
embryo. (Embryo IX, 9.) 
Fig. 6 Sagittal section through an embryo, a portion of the spinal cord of 
which has been reversed. A transposed portion of the medullary ventricle is 
clearly to be seen. (Embryo IX, 13.) 
