94 THE ROYAL SOCIETY OF CANADA 



described them as nervous elements, and Lang (31) seemed to prove 

 their connection with the nerves for ectoparasitic forms (Tristomum). 

 In Poirer's (32) paper I find them called ganglion cells; Schuberg 

 (33) states that staining with methylene blue shows them to be exactly 

 like nerve cells. Otto (34) also calls them ganglion cells. Looss (29) 

 himself after careful study, concluded that the "grossen zellen" were re- 

 mains of the original formative cells of the sucker and pharynx from 

 which the muscle fibres differentiated, which wandered in with the 

 growth of the parenchyma cells and together with these formed the.con- 

 nective ground substance of the suckers. Walter (25) described them, 

 both in the body parenchyma and in the suckers, as intermediate 

 stages in the formation of ordinary parenchyma cells, from the subcuti- 

 cular layer. Leuckart in the "Parisiten des Menschen" called them 

 formative cells of the radial muscles of the suckers. Nicholls (36) 

 calls them "myoblasts," he says they have little in common with 

 the "subcuticular glands," but resemble very nearly nerve ganglion 

 cells. Villot (37) and after him Mace (38) considered the "great" 

 cells as "Dilations vasculaires," or merely sections of vascular, that 

 is excretory tubules (39). Wright and Macallum suggest that they 

 are connected with the excretory system. Braun (40) proposes that 

 they may assist in increasing the elasticity of the organs in which they 

 lie and act especially as "antagonists" to the radial muscle fibres. 

 My own observations lead me to conclude that the "large" cells are 

 remains of embryonic parenchyma cells which have enormously 

 increased in size and like "Giant cells" have lost the power of dividing 

 mitotically but may break up by direct division. As for their function 

 the conflicting views may be partly reconciled by regarding them as 

 myoepithelial cells. 



In conclusion I wish to express my sincere thanks to Professor 

 Willey for the help he has so generously given me in my study, and 

 in the final revision of this report of my work. 



