398 



SPECIFIC MICRO-ORGANISMS 



on blood-agar plates. The organism is not known to be capable 

 of infecting vertebrates. 



Somewhat similar flagellates are found in the alimentary 

 tract of various insects, where they may be easily mistaken for 

 developmental stages of hematozoa. Trypanosoma {Herpeto- 

 monas ) grayi which is found in the tsetse fly Glossina p^lpalis 

 may be mentioned as another example. 



Fig. 155. — Leptomonas culicis from the digestive tract of 'a' mo squito. 

 (After Novy, MacNeal and Torrey.) 



XiSoo 



Tr3T)anosoma Rotatorium.^This organism is the type species 

 of the genus Trypanosoma, as this name was first applied to it by 

 Gruby in 1843. It is commonly found in small numbers in the 

 blood of frogs. The form of the cell varies from that of a slender 

 spindle to a very broad and thick structure (Fig. 156). The 

 widtt varies from 5 to 40A1 and the length from 40 to 8om. These 

 various forms are probably stages in the growth of the parasite but 

 it is not impossible that they represent different species parasitic 

 in the same animal. When the larger forms are well stained the 

 typical structures of a trypanosome are distinctly evident. The 

 large nucleus (trophonucleus) lies near the middle of the body 

 and closer to the undulating border. Posterior to it is the smaller 

 and more deeply stained blepharoplast. Close to the latter a 

 small clear colorless area is commonly seen. The flagellum 



