448 



VETEEINAEY HYGIENE 



Africa, where it causes 'sleeping sickness,' first seen in 

 Uganda. 



Some harmless trypanosomata are known to exist as 

 parasites in the blood of some small vertebrates, batra- 

 chians, and fish. 



Sporozoa.— The coccidias are parasites affecting the cell ; 

 they exist in two stages the result of sexual dimorphism. 

 One stage, the Schizogenic is the means by which the 

 organism multiplies within the body for the purpose of 



c, /^•^^ 



Fi£c. 15 



-Diagram of the Cycle of Development of H;emoproteus. 

 Scliaudim.)* 



(After 



1, Sporocysts entering the red corpuscle ; 2 to 4 are the scMwgeiiic stages 

 by which the organism multiplies in the body for the further infection of the 

 host. Within the body it never goes beyond Stage 4, and from this infects 

 otiier blood corpuscles as indicated by the arrow. 



Stages 5 to 11 are sporogcnic, and serve for the reproduction of the species, 

 5 being the male, 5a the female element, 6 and 6a being the mature cell 

 elements ; these come together at 7, resulting in the formation of an oocyst at 

 8, and finally the production of a mature sporocyst at 11, which when 

 inoculated into an animal infects the red cell. Stages 5 to 11 take place 

 outside the animal body and within that; of the intermediate host. 



infecting its host (Fig. 186), the other, or Sporogenic 

 stage, is a true sexual reproduction by male {macrogamet) 

 and female (microgamet) elements, which serves not for the 



* Dr. F. Dofiein, Die Protozen. 



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