178 G. E. COGHILL 



granules appear in the connecting filaments. Some of these 

 granules appear to be suspended in distended portions of the 

 filament-like particles in a slender pseudopodium. They are 

 near the spinal cord and have the same characteristics as the 

 pigment granules that appear in the peripheral portions of the 

 cord. This relation suggests that these filaments are outgrowths 

 of the cells of the spinal cord and that the larger adhesions may- 

 be secondary and not primary arrangements of the parts. 



The giant ganglion cell of figure 20 has already been mentioned 

 as sending its axone into the area of adhesion just described. 

 From the basal portion of its process arises a small filament 

 which is conical at its base and the internal structures of which 

 merge into those of the cell. Other small filaments, apparently 

 of epithelial ^origin, occur just caudad of this (the section is 

 inclined from the dorsal side cephalad and ventrad). Farther 

 cephalad is one of the characteristic connectives between the 

 spinal cord and the skin. In this is a small yolk spherule. This 

 inclusion has important bearing on the nature of the filament, for 

 yolk is exclusively intracellular in its early embryonic relations 

 in these animals. Therefore, since there are no mesenchymal 

 cells in the vicinity to which the filament can belong, it must 

 be either an integral part of a cell of the spinal cord or skin, or 

 a syncytial connective between cells of the cord and skin. Further 

 evidence of the cytoplasmic nature of these connectives will 

 appear in the following paragraph. 



Figure 21 illustrates a region of contact between the spinal 

 cord and the skin in which the adhesion of the giant ganglion 

 cell to the skin is accidentally shown. The lower part of the 

 figure is directed caudad, so that the process of the giant ganglion 

 cell (the most caudal of a group of three) must be regarded as an 

 ascending process. Here again the rent between the outer and 

 inner layers of the epithelia of the skin shows evidence of a pull 

 having been exerted upon the outer surface of the skin. This 

 probably occurred in the manipulation of the cut sections while 

 they were being adjusted upon the slide. The adhesion of the 

 fiber of the giant ganglion cell to the skin is shown by its relation 



