Chapter 24 

 Class 3 Sporozoa Leuckart 



THE Sporozoa are without exception parasitic and bear spores. 

 Their hosts are widely distributed in the animal kingdom, from 

 Protozoa to Chordata. As a rule, they are incapable of locomotion, 

 but some when immature may move about by pseudopodia or myo- 

 nemes. They possess neither cilia nor flagella, except in the gamete 

 stage. In the forms that are confined to one host, the spore is usu- 

 ally enveloped by a resistant membrane which would enable it to 

 withstand unfavorable conditions while outside the host body, but 

 in those having two host animals, as in Plasmodium, the sporozoite 

 is naked. The method of nutrition is saprozoic or parasitic, the food 

 being dissolved cytoplasm, tissue fluid, body fluid, or dissolved food 

 material of the host. 



Both asexual and sexual reproductions are well known in many 

 species. Asexual reproduction is by repeated binary or multiple fis- 

 sion or budding of intracellular trophozoites. The multiple division 

 in a host cell produces far greater number of individuals than that 

 of protozoans belonging to other classes and often is referred to as 

 schizogony. The sexual reproduction is by isogamous or anisogamous 

 fusion or autogamy and marks in many cases the beginning of 

 sporogony or spore-formation. 



Schaudinn (1900) divided the Sporozoa into two groups, Telospo- 

 ridia and Neosporidia, and this scheme has been followed by several 

 authors. Some recent writers consider these two groups as separate 

 classes. This, however, seems to be improper, as the basis of dis- 

 tinction between them is entirely different from that which is used 

 for distinguishing the other four classes: Sarcodina, Mastigophora, 

 Ciliata, and Suctoria. For this reason, the Sporozoa are placed in a 

 single class and divided into three subclasses as follows: 



Spore simple; without polar filament 



Spore with or without membrane; with 1-many sporozoites 



Subclass 1 Telosporidia 



Spore with membrane; with one sporozoite 



Subclass 2 Acnidosporidia (p. 635) 



Spore with polar filament Subclass 3 Cnidosporidia (p. 643) 



Subclass 1 Telosporidia Schaudinn 



The spore which contains neither a polar capsule nor a polar fila- 

 ment possesses one to several sporozoites and is formed at the end of 

 the trophic life of the individual. In the forms which invade two host 



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