PROTOZOA AND DISEASE. 121 



called Leishman-Donovan body, the parasite of dum-dum 

 fever or splenomegaly, a disease occurring in India and 

 Africa, has recently been shown to be a stage in the 

 life history of a flagellate protozoon. Of great import- 

 ance, also, is the family of Spirochaetes, one of which, 

 Treponema (Spirochate) pallidum^ is the organism which 

 causes syphilis. Another highly important genus is Piro* 

 plasma (Babesia\ a sporozoon. These are blood parasites, 



FIG. 54. 



i. Trypafiosoma gambiense, showing nucleus, blepharoplast, 



and flagellum. 



2 and 3. Individuals undergoing longitudinal fission. 

 4. Leucocyte engulfing a trypanosonie. 



causing Texas fever in cattle and A analogous diseases in 

 horse, sheep, dog, and possibly man also. The parasite 

 of Texas fever is transmitted through two generations 

 of ticks. Lastly may be mentioned the parasites of 

 malaria, Laverania and Plasmodium, whose compli- 

 cated life histories in mosquito and man are now well 

 known. 



General zoological interest. The Protozoa illustrate, in 



