4 GENERAL EMBRYOLOGY 



is more frequently termed spore formation or sporulation and 

 the products are known as swarmspores or zoospores. Tech- 

 nically the term sporulation or sporogony (metagametic division) 

 is used only when this process of multiple fission occurs sub- 

 sequently to a process of cell fusion. If no such process of 

 cell fusion or conjugation has preceded, the process is termed 

 schizogony (agamogony) , and the products of the division are 

 called schizonts (agamonts). 



FIG. 3. Multiple fission (schizogony) in the Sporozoan, Coccidium schubergi. 

 After Schaudinn. A. Entrance of organism ("sporozoite") into epithelial cell 

 of host. B, C. Two stages in growth. D. Multiple division of nucleus. E. 

 Daughter nuclei superficial, cytoplasm still undivided. F. Fission of the super- 

 ficial cytoplasm surrounding the nuclei, leaving a central undivided mass. G. 

 Free schizonts ("merozoites"). 



Reproduction by analogous processes also called fission, 

 simple or multiple, is only occasional among the many-celled 

 animals. In a few such forms the entire body separates as a 

 unit into two or more organisms. Organs and tissues in the 

 plane of separation are divided, and each of the daughter or- 

 ganisms then regenerates parts corresponding to those carried 



