52 



SPOROZOA. 



Mature trophozoite intracellular and small. 

 Zygote non-motile ; sporozoites within 



a spore Coceidia Leuckart, p. 113. 



Zygote motile ; sporozoites without [sky, em. Doflein, p. 209. 

 envelope Hsemosporidia Danilew- 



I. Order GREGARINIDA A.Schneider, 

 emend. Doflein, 1901. 



The Gkbgaeinida are chiefly ccelozoic or lumen-dwelHng 

 parasites of Invertebrates, especially Arthropods and Annehds, 

 usually inhabiting the digestive tract, less frequently the 

 ccBlome or the vascular system. They are typically intra- 

 cellular only in the early part of their growth, i. e., in the 



Fig. 3. — Life-cycle of a typical Eugregarine. A, syzygy ; B, union 

 of two sporonts ; C, encystment of the two sporonts and 

 nuclear multiplication in each ; D, arrangement of the 

 nuclei on the surface (pearl stage) ; E, gamete formation ; 

 F, gametes set free and their union in pairs ; G, cyst con- 

 taining the spores ; H, liberation of the spores through the 

 sporoducts. (From Reichenow, after Rahler, Schnitzler, and 

 ScheUack.) 



trophozoite stage. Later they leave the epithelial cell and 

 develop into more or less elongate motile adults, usually 

 referred to as Gregarines. The vast majority of the Gregari- 

 NiDA do not show asexual reproduction or schizogony, and 

 multiphcation takes place solely by sporogony following 

 upon gametogony. The adult Gregarines or sporonts are 

 gametocytes, but do not show a differentiation into male or 

 female gametocytes, which is a characteristic feature of the 

 CocciDiA and the H^mosporidia. The gametocytes associate 



