196 



EMBRYOLOGY 



The Cysticercus may remain for a longer or a shorter time 

 in the condition described, but may increase meantime in 



Fig. 96.—^ to JT, development of tlie tnpeworm from embryo to scolex (after 

 Leuckakt). yl, six-hook embryo ; B, Cysticercus of Tceii in sngi'imfn ; C to J-J, cephalic 

 process of the hydatid {Cysticercus pisiformis) of T. sagivatn : C, before the funda- 

 ments of the suckers and hooks have iLade their nppearance, D, with fundaments 

 of the hooks and suckers, E, in the partially evaginated condition : F, fully evagi- 

 nated cephalic process with attached vesicle of T. aolium ; G, scolex of T. senvila 

 with the remains of the vesicle, which has fallen away ; H, young tapeworm (T. 

 serratii), which has only just left the scolex stage, and in which there are therefore 

 only a few segments. 



vertebratecl animals, especially in Crustacea [e.p. Gammarus and Cyclops), 

 are very noteworthy ; their relationships, however, are not yet suHiciently 

 understood. The caudal appendage, which sometimes attains a very 

 considerable length, carries about with it the remains of the embryonal 

 envelopes. This stage in the development of the Cestodes thereby 

 acquires to a certain extent the appearance of a Cercaria. Such tail- 

 bearing Cysticerci, which belong especially to the genus Tamia, have 

 been repeatedly discovered in recent years, and carefully studied by 

 Hamann, MitAZEK, and Grassi e Rovelli (see Appendix to Literature on 

 Cestoda).— K.] 



