PROTOZOA 37 



in the local habitat or met with in the course of the distribution of the 

 species (e.g. freshwater forms and parasites); and that at this time 

 (a) the ordinary agamogony is suspended, (b) the syngamy, if any, 

 usually takes place, (c) there is often a phase of protective encystment, 

 (d) there is often very rapid multiplication by multiple or repeated 

 fission, which may be the sporogony, the gamogony (eugregarines), 

 or an agamogony; 



(3) that any part of the cycle may be omitted ; in such cases it is 

 most often the sporogony which is dropped, but many species appear 

 to omit gamogony, and in a few (e.g. Monocystis and the other eugre- 

 garines) there is no agamogony; 



Agamont (Schizont, Meront) 



Agamogony (Schizogony, Merogony) 

 Agametes (Schizozoites, Merozoites) 

 Growth of Agametes 



Agamont of second generation 



Agamogony repeated 



Gamont 

 Gamogony 

 Gametes 

 Syngamy 

 Zygote (Sporont) 



Sporogony 

 QQ © © © Sporozoites 



/ 







Growth of sporozoite ■ 

 Agamont 



Fig. 29. A table of the life history of a protozoon. 



(4) that a reduction division may occur at either of two points in the 

 cycle — shortly before syngamy (most cases), or directly after the 

 formation of the zygote (the Telosporidia and Volvocina) — and that 

 correspondingly either the diploid or the haploid phase may extend 

 over the greater part of the life history. 



The term spore is applied to various phases of the life history in a 

 way which is liable to cause confusion, {a) Strictly speaking, perhaps, 

 it should be applied only to the products of repeated or multiple 

 fission of a zygote (sporont). (b) Most often, however, it is used to 

 denote the products of any repeated or multiple fission, {c) In a few 



