The Histogenesis of Cysticercus pisiformis. 217 



cells lies in their striking similarity to the ganglion cells of the 

 nerve cords. Both kinds of cells are tj^picallj' bi-polar, altho ex- 

 ceptions to this rule exist as will be noted later. In each the nucleus 

 is typically deeply-staining and presents apparent continuity with 

 the fibrillar cytoplasm of the cell, which fibrillae are present in 

 both kinds of cells and present the same relations in both. They 

 vary in size to some extent, pursue a tortuous course thru the cell 

 process into its fibre, crossing one another in their course. It is 

 probable that they anastomose but of this I cannot speak with 

 certainty. Some of the neuro-muscular cells present the same 

 appearance as is described and figured by Rössler (figs. 16 and 17). 

 This I attribute to a probable grouping and separation of the fibrillae. 

 I have not observed it in the neurons of the central nervous system. 

 It is very possibly an artifact resultant upon the action of the 

 methylen blue treatment. In this connection it is interesting to 

 note that, in "myoblasts"' stained with methylen blue, the nucleus 

 has contracted leaving a narrow clear zone surrounding it. This 

 is most probably an artifact, since it has not been observed in 

 cells stained by any other method than with methylen blue. 

 This appearance has been noted by Rössler and figured by him 

 (fig. 13). Apparently he, however, does not consider this an artifact. 

 The neuro-muscular cells in the suckers are very irregular multi- 

 polar cells, closely resembling the parenchyma cells and in many 

 instances indistinguishable with certainty from the latter. They 

 may, however, usually be distinguished by their larger size and less 

 deeply stained nuclei. During development they may usually be 

 readily distinguished from the parenchyma cells as large cells with 

 large round nuclei containing one or more nuclear granules, while 

 the nuclei of the latter are mostly very deeply stained and the cell 

 body is more irregular than that of the "myoblasts". In some places 

 small nerves may be seen in the suckers or passing in from without; 

 but these nerves cannot be traced continuously for ruj distance. 



An apparent lateral connection of a nerve fibre with a "myo- 

 blast" such as is shown by Rössler in fig. 21 has also been occasion- 

 ally seen. The presence of sense cells has not been demonstrated. 



A special type of "binding cell", such as has been described 

 by ToAVEE (1900) in the nervous system of Moniezia expansa, Zernecke 

 (1895) on the nerve cords of Ligula, and others, cannot be demon- 

 strated in Cysticercus pisiformis. Parenchyma cells are 

 present along the cords and send their processes into the latter, 



15* 



