THE ILEMOSPORIDIA 397 



form probably used its flagellum for the purpose of attaching itself 

 to the epithelium of the digestive tract, as leptomonads do now 

 (compare Figs. 136, 137) ; and from this primitive type of attach- 

 ment the epimerite of the gregarines may have been derived by 

 secretion of chitin round the attaching flagellum, just as the 

 primitive tuft of fixing cilia, the " scapula," of the primitive 

 Vorticellids appears to become converted into the chitinous stalks 

 of such forms as Epistylis (p. 441). 



The conclusion drawn from these various considerations is, 

 therefore, that the Telosporidia may be regarded as a group de- 

 scended from flagellate ancestors modified in adaptation to a para- 

 sitic mode of life ; not, however, specially from flagellates of the 

 " binucleate " type of structure. 



Bibliography. For references see p. 496. 



