IO 



CHAPTER II. 



THE diseases caused by sporozoa are of special im- 

 portance as they include those caused by the parasites 

 of malaria as well as trypanosomiasis, one form of 

 dysentery, and other ailments. They are therefore con- 

 sidered first, and with them other diseases, probably 

 caused by allied parasites. 



The classification of the Sporozoa is still in dispute, 

 and various schemes have been propounded from time 

 to time. There is no authoritative classification at 

 present. The scheme here given is a useful one, but 

 is not to be regarded as final or as even universally 

 accepted. 



SPOROZOA. 



(A) Those in which the entire protoplasm, with the 

 exception of dead residual masses, divides into spores, 

 the parent protozoon disappearing in the process. 



Telosporidia, e.g., parasites of malaria, coccidia, &c. In 

 this group are included the sporozoa that cause the most 

 important diseases of man and the lower animals- 

 malaria, Texas fever, &c. 



The group is variously divided by different authors and 

 protozoologists. The classification here given is con- 

 venient for the purpose : (i) Gregarinida; (2) Coccidia ; 

 (3) Hcemosporidia ; (4) Hcenwgregarinida. 



(i) Gregarinida. The body is of a constant elongated 

 form. They are distinguished by their peculiar creeping 

 movements. They are parasitic in cells of the intestinal 

 walls of the various invertebrates during the early part 

 of their existence, and later are free in the intestinal 

 cavity or its appendages, where they become encysted, 



