THE NERVOUS SYSTEM OF AMPHIBIA 177 



mediately beneath the skin. Filaments from this region reach 

 to the skin; others are directed towards the myotome. 



Another direct connection of the giant ganghon cell with 

 the skin in a non-motile embryo is illustrated in figure 18. This 

 fiber occurs between the ninth and tenth myotomes. As in the 

 case of figure 8, the fiber connects with the projection of the skin 

 into the space between the myotomes. 



Figures 19 to 21 are intended to show the intimate relation 

 that holds between the skin and the spinal cord in the caudal 

 region of the non-motile embryo, and the place that the giant 

 ganghon cells hold in this region. These figures are taken from 

 the level of the unsegmented mesodenxi. In figure 19 the skin is in 

 immediate contact with the spinal cord. Tn the region of the 

 most intimate contact, where there is no perceptible boundary 

 between the two structures, is a small mass of densely fibrillated 

 substance. This, upon being traced caudad, is found to be con- 

 tinuous with the giant ganghon cell shown in figure 20. Dorsad 

 of this region of most intimate attachment is another attachment 

 of smaller extent and less intensive adhesion. Still more dorsad 

 is an attachment which consists of filaments between the two 

 structures. That there is here strong adhesion between the 

 skin and spinal cord is evidenced by the rent that appears 

 between the outer and inner layers of cells in the skin. There has 

 been from some source a pull upon the outer layer of epithelial 

 cells, tending to separate the skin from underlying structures, but 

 the adhesion of the inner layer of epithelial cells to the spinal 

 cord has proved stronger than that to the outer layer of epithe- 

 lial cells. On the opposite side of the cord, also, in this section 

 is the same evidence of adhesion and pull. Tn this side, however, 

 the skin is partially pulled away from the spinal cord so as to 

 tear out some of the fibrillar structures. These retain their con- 

 nections in the cord at one end while they are attached to the 

 skin at the other. 



In the next section caudad from that of figure 19 the more dor- 

 sal and smaller of the adhesions in this figure gives place to 

 fibrillar strands between the skin and spinal cord, and pigment 



THE JOURNAL. 01 COMPARATIVE NEUROLOGY, VOL. 24, NO. 2 



