THE GREGARINID^. 



87 



or elongated oval bodies, sometimes divided by constrictions 

 into segments. Occasionally, one end of the body is pro- 

 duced into a sort of rostrum, which may be armed with re- 

 curved horny spines. 



In the ordinary Gregarmcc, the body presents a denser 

 cortical layer (ectosarc) and a more fluid inner substance 

 (endosarc), in Avhich last the endoplast (nucleus) is imbed- 

 ded. The presence of contractility is manifested merely by 

 slow changes of form, and nutrition appears to be effected by 

 the imbibition of the fluid nutriment, prepared by the organs 

 of the animals in which the Gregarinm are parasitic. There 

 is no contractile vacuole. 



The Gregarinm have a peculiar mode of multiplication, 

 sometimes preceded by a process which resembles conju- 

 gation. A single Gregarina (or two which have become 

 applied together) surrounds itself with a structureless cyst. 



Fig. l.—A, Gregarina of the earthworm (after Lieberkiihn); B. encysted; C, 2), 

 contents divided into pseud o-navicellae ; E^ F, free pseudo-navicellae , G, H, free 

 amoebiform contents of tlie latter. 



The nucleus disappears, and the protoplasm breaks up (in a 

 manner very similar to that in which the protoplasm of a 



