66 



THE ANIMAL PARASITES OF MAN 



protoplasm. A small portion of the protoplasm gal hers round each 

 nucleus, and a number of small cells, hitherto called sporoblasts, are 

 formed (fig. 23) on a large unused residue of protoplasm (residual body, 

 sporophor). As, however, these formations coalesce in pairs, as has been 

 discovered by Siedlecki and Cuenot, they must be called gametes. They 



FIG. 24. Monocystis sp. from the vesicula seminalis 

 of earth-worms 14001. (a) Spore with spore cuticle 

 developed ; (b) mature spore with sporozoits and 

 residual bodies ; (c) optical transerve section of mature 

 spore (after Biitschli). 



appear to be completely alike, but it is very probable that each one of the 

 couple is the product of one of the sporonts ; in accordance herewith the con- 

 jugation or copulation would be isogamous. 1 The designation sporoblast 

 hitherto in use may be applied to the product of amalgamation. They are 

 transformed into spores, assuming a more fusiform shape, and they secrete a 

 covering of the same shape, within which the enclosed cells, after repeated 

 mitotic division of the nucleus, divide -up into a certain number (usually 



a. 



d. 



FIG. 25. Spores of various gregarines. (a) of Porcspora (b) of Xi\. 

 of AncyroQhora ; (d) of Gonospo'ra ; (e) of Ceratospora. (After Leger. 



(b) of Xiphorhynchus ; 



eight) of elongated fusiform, or sickle-shaped little bodies, the sporozoites. Even 

 in this process a small residual body remains, around which the sporozoites 

 are grouped (fig. 24), 



The development of a covering for the spores is lacking in Porospora ; 



1 The A mphimixia here instanced cannot, however, take place in the cases in which 

 one gregarine alone is encysted., or in which one of the two encysted individuals dies 

 off, and the other then sporulates alone. Accordingly A mp hi mixia is not necessarily 

 connected with the conjugation of the gametes. 



