CHAPTER XXI 



CLASS 3 SPOROZOA LEUCKART 



ALL SPOROZOA are parasitic and produce spores. As a rule, 

 1\. they are incapable of movement, but some when im- 

 mature move about by means of pseudopodia. They have no 

 cilia or flagella. In the forms that are confined to one host, 

 the spore usually possesses a resistant envelope to withstand 

 unfavorable conditions. In those having two hosts, as in Plas- 

 modium, the sporozoite does not have a definite membrane or 

 wall. 



The method of nutrition is by osmosis only. The food ma- 

 terial absorbed from the host, may be dissolved cytoplasm, 

 tissue fluid, body fluid, or dissolved food material in the diges- 

 tive tract of the host. 



Both asexual and sexual reproduction are known in num- 

 erous forms. Asexual reproduction is by binary or multiple 

 fission, or by budding. The rate of division of the trophozoite 

 is much greater than that of protozoans belonging to other 

 classes, and this results in the formation of a large number of 

 individuals. This multiplication is collectively known as the 

 schizogony (or agamogony), and the products are schizonts (or 

 agamonts, merozoites). The sexual reproduction is by isogam- 

 ous or anisogamous copulation or autogamy. This reproduc- 

 tion marks the beginning of the sporogony, or spore-formation, 

 and the initial stages are called gametocytes, or sporonts. In 

 some groups sexual reproduction has not been clearly observed. 



The Sporozoa are parasitic in animals of almost every phy- 

 lum from Protozoa to Chordata. Numerous important para- 

 sites are, therefore, placed in this group. Schaudinn divided the 

 Sporozoa into two groups, Telosporidia and Neosporidia, and 

 this scheme has been followed by several students. Some 

 recent authors consider these two groups as separate classes. 

 This, however, does not seem to be wise, as the basis of dis- 

 tinction between them is entirely different from that used for 



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