68 



STL7RGES. 



[VOL. I. 



base. The different parts of the papillae may be brought into 

 view by focussing on tangential sections of the body wall. 



(d] The processes which spread out into plexuses cannot be 

 followed far, for after the outline of the process is lost, it is 

 easy to deceive oneself. The same is true in the case of the 



ultimate fibrils of the 

 ventral nerve and those 

 passing from the sensory 

 papillae. I cannot, there- 

 fore, assert that a con- 

 tinuous s u b c u t i c u 1 a r 



i s^^g&t^szjfTflw plexus is formed by proc- 



esses of the giant-cells 



and ultimate branches of 

 the nerve-trunks, yet the 



facts suggest this. I 

 hope to test fresh mate- 

 rial on this point with 

 special methods. Bloch- 

 mann and Zernecke find 

 the peripheral plexus in 

 Cestodes within the sub- 

 cuticular cells, while here the indications are that it lies outside 

 of them, within the dermal muscles. Blochmann and Betten- 

 dorff state that a nervous plexus exists within the subcuticular 

 cells in Trematodes, but their preliminary paper gives no satis- 

 factory description or figures of it. 



These facts seem to indicate that the giant-cells are not 

 myoblasts but true ganglion cells, some of which have retained 

 a primitive character so that they lie at the periphery and 

 innervate both muscles and sense-organs, either directly or 

 through a peripheral plexus. The nervous system is simpler 

 here than in Cestodes, for one cell, the giant-cell, does the 

 work which in Cestodes is assigned to three, -- sense-cell, gan- 

 glion-cell proper, and myoblast. This slight differentiation in 

 the sensory-motor system reminds one of the instances men- 

 tioned by Zernecke where he found in Cestodes a direct connec- 

 tion between sense-cell and myoblast. 



_ r 



FIG. 3. Tangential section of body wall, cm, circular 

 muscle ; /in, longitudinal muscle ; y, process of giant- 

 cell ; z, process innervating muscle. 



