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Th e Schizogregarines 
Sporoblast. A uninucleate mass of protoplasm arising from a zygote. A sporoblast 
gives rise to sporozoites. 
Sporocyst. The tough chitinoid membrane secreted on the outer surface of a sporoblast. 
A sporocyst enclosing eight sporozoites is often termed an octozoie spore. 
Sporogony. The formation of resistant spores from a zygote, following upon a sexual act. 
This process is sometimes termed exogenous reproduction, and serves for the 
infection of new hosts (cross-infection). 
Sporozoite. A fine, curved, falciform, naked mass of protoplasm formed from a sporo¬ 
blast. The sporozoite is the agent which starts an infection. 
Sporulation. A method of rapid multiplication by the formation of reproductive bodies 
(spores), each of which is a fragment of the parent body. 
Trophozoite. An individual Sporozoon during its trophic phase, that is, during the time 
the parasite is absorbing nutriment from its host and is growdng rapidly. The 
trophic period is one of “ vegetative ” growth. 
A trophozoite may become either a schizont or a gametocyte. 
Zygote. The individual resulting from the fusion of two gametes. 
