366 



BIOLOGY OF THE PROTOZOA 



These parasites have no mouth, food-taking being osmotic or 

 saprozoic. They live, normally, in the dissolved food substances 

 of the gut or in the blood but may grow and multiply in the semi- 

 fluid protoplasm of different types of tissue cells. For the most 



Fig. 169. — Trypanosomidae. A, Leptomonas ctenocephali; B, Herpetomonas mus- 

 carum, at left individual in division, at right trypanosoma form. C, Phytomonas 

 davidi; D, Trypanosoma gambiense; E, macrophage with intracellular phase of Leish- 

 manial donovani; F, Leishmania donovani, flagellated and division stages; G, Crith- 

 idia gerridis from water bugs; H, Endotrypanum schaudinni in blood of sloth; I, 

 Trypanosoma rhodesiense. X ca 2000. (After Wenyon, Protozoology, 1926; courtesy 

 of Bailliere, Tindall & Cox.) 



part they grow readily in culture media which must be kept free 

 from bacteria. Novy and MacNeal (1904) were the first to culti- 

 vate Trypanosoma in the condensation fluid of solid blood agar, 

 their method being somewhat simplified by Nicolle and now gener- 



