50 SPOROZOA. 



Phylum PROTOZOA. 



Class SPOROZOA Leuckart, 1879. 



Protozoa which are exclusively parasitic in their mode of 

 life, and Uve in the cells or body fluids of Vertebrate or Inverte- 

 brate hosts. They produce resistant spores at some stage 

 or another of their hfe- cycle. 



The general organization of the class and the basis of classi- 

 fication into subclasses and orders has already been discussed. 

 Following Reichenow, the class Sporozoa is divided into 

 four subclasses, as follows : — 



1 (2). Trophic and reproductive phases typi- 

 cally distinct ; trophozoite becoming 



fully developed before reproduction [Schaudinn, p. 50. 



begins. Sporozoites are Gregarinulse . Telosporidia 



2(1). Trophic and reproductive phases usually 

 overlap ; the still-growing or even quite 

 yoiuig trophozoite may begin to form 

 spores. Sporozoites are Amcebulse ... 3. 



3 (4). Spores with one or more thread-cap- [p. 328. 



sules Cnidosporidia Doflein, 



4 (3). Spores without thread-capsules 5. 



5 (6). Cysts forming long rod-like masses 



(Miescher's tubes). Spores crescentic, 

 with one end rounded and the other 

 pointed. Parasites of striped muscle [p. 361. 



of Vertebrates Sarcosporidia Balbiani, 



6(5). Spores large, containing a single voliimi- 



nous nucleus. Simple type of develop- [& Mesnil, p. 369. 



ment Haplosporidia CauUery 



I. Subclass TELOSPORIDIA Schaudinn, 



1900. 



Telosporidia are Sporozoa in which the trophic and 

 reproductive phases are typically distinct, the animal becoming 

 full grown before either asexual reproduction {schizogony) or 

 sexual reproduction {gamogony or sporogony) begins. 



The great majority are intracellular parasites, at least 

 during part of their life-history. The parasites are uninucleate 

 in the early period of growth. During growth (as in Coccidia 

 and H^mosporidia). or after growth is completed (as in 

 Gregarinida), the nucleus divides by repeated mitotic 

 divisions, and the organism breaks up into as many daughter 



