III. SPOROZOA: GREGARINA 



187 



Reproduction typically occurs in an encysted condition (fig. 145, II). 

 Usually two animals occur in a cyst. After each individual has become 

 polynucleate by division of its nucleus, it divides at first superficially, 







Fig. 145. — Different Gregarina. I-VII, development of Stylorhynchus; I, 5. 

 Imigicollis (after Schneider); II, encysted 5. oblongatus (two animals) beginning 

 gamete formation; III, same in later stage, the sexually differentiated gametes in 

 copulation; IV-VII, formation and development of the zygote of 5. longicollis more 

 enlarged; IV, copulation of gametes; V, fusion; VI, beginning division; VII, 

 8, sporozoites formed. A. Clepsidrina blattarum. 1-4, Monocystis magna (after 

 Cuenot). I, two individuals in copulo in the spermatheca of an earthworm, sur- 

 rounded by its spermatozoa; 2, encysted; 3 and 4, parts of cysts, formation and con- 

 jugation of the gametes, more enlarged (according to Brasil the gametes are slightly 

 diiferentiated sexually), cu, cuticula; dm, deutomerite; ek, ectosarc; en, entosarc; g, 

 gametes; g\ zoospores, g-, oospore; pm, protomerite; n, nucleus; r, residual body; s, 

 sperm of earthworm; z, zygote. 



later internally into small spheres, the gametes (III). The gametes fuse in 

 pairs to bodies which take a spindle shape and become enclosed in a firm 

 envelope, the spores, zygotes or 'pseudonavicellas' (fig. 145, 4, IV — VI). 



