1 84 



THE SPOROZOA 



the type described above for Monocystis, or takes place in a manner 

 easily deducible from it (Fig. 29). In Monocystis, Lankesteria, 

 Diplocystis, etc., there is perfect isogamy ; the conjugating gametes 

 are not distinguishable from one another, and do not fall into 

 two classes. In the Cephalina, on the other hand, anisogamy 

 of a highly differentiated type appears to prevail. In Stylo- 

 rhynchus L6ger [23] has recently described anisogamous conjugation 



FIG. 28. 



Cyst of Gregarina laucourwtensis (A. Schn.) (par 

 Parnus sp.) with a single, very elongated sporo- 

 duct. (From Wasielewski, after Aime Schneider.) 



of a very interesting type. Two sporonts associate and become 

 encysted together : one of them gives rise to motile active gametes 

 termed male, the other to non-motile passive gametes termed 

 female. The sporonts themselves, therefore, may be considered 

 to be potentially male and female. Each sporont occupies one- 

 half of the cyst, so that a male and a female chamber can be 

 distinguished. Each sporont breaks up into a number of primary 

 sporoblasts or gametes, and at first the gametes formed in each 

 chamber are simply little protoplasmic spheres (Fig. 30, a), as in 



