SPINAL CORD REGENERATION. II 435 
continued to develop in their normal orientation to that piece 
and that the transposed portion of the medullary ventricle 
remained,,with but minor changes, normal. During the early 
stages of development and up to a time after the healing has 
been completed, there is not a single sign that the polarity of the 
cord has been reversed. 
Fig. 7 Frontal section through an embryo in which a relatively large part 
of the medullary ventricle (seen at the left) was reversed. 
Fig. 8 Graphic reconstruction of the same embryo. (Embryo IX, 12.) 
Fig. 9 Sagittal section through the central nervous system and notochord 
of an embryo in which a small portion of the spinal cord was reversed. The 
right hand piece of the notochord marks out the length of the segment reversed. 
It will be noted that the central canal of the spinal cord has apparently enlarged 
at the point of fusion with the medulla anteriorly. Posteriorly a piece of the 
notochord became inserted between the wound surfaces, necessitating the diverg- 
ence of the developing nerve fibers from the normal course. In spite of the 
cavity in the spinal cord in which this piece of notochord hes, a return to nor- 
mal function was obtained. This section is from the embryo shown in figure 1. 
(Embryo IX, 5.) 
