PROTOZOA. 



73 



of daughter cells simultaneously, the process is called schizogony and the 

 young parasites are called merozoites, if a sexual fertilization has not 

 preceded the act of division; if such a division, in which the parent organ- 

 ism disappears, takes place after a fertilizing act, the process is called 

 sporogony and the young parasites are sporozoites. 



FIG. 46. Coccidium schubergi. A-C, asexual multiplication; D-K, sexual multi- 

 plication; Z), microgametes; E, macrogamete; F, G, fertilization; H, I, K, division and 

 spore production. (After Schaudinn, from Dqflein.) 



In protozoa, as in metazoa, the essential process in fertilization is the 

 union of two nuclei of opposite sex. Before union, these nuclei undergo 

 a series of divisions, in which the number of the chromosomes is reduced 

 and polar bodies are extruded. In dividing, almost all cells go through 

 a process called mitosis. In mitosis, the chromatin of the nucleus is 



