The Blood Flagellates 591 



from 41° S. (Patagones, Buenos Aires, Argentina) to 38° N. latitude 

 (Pinole, California). Within this range, the trypanosome has been re- 

 ported from a number of mammalian hosts and from a variety of insects. 

 In addition to Trypanosoma cruzi, the similar T. rangeli has been re- 

 ported from man, dogs, and reduviid bugs in South America (55a). 



Panstrongylus megistus (Triatoma megista) was the first insect identi- 

 fied as a vector of T. cmzi (12). Since 1909, more than 30 species of 



Fig. 12, 3. Trypanosoma cruzi. A. Stages in the digestive tract of the 

 vector; schematic (after Lent). B. Trypanosoma! stage from blood, x2800 

 (after Wenyon). C. Leishmanial forms in heart muscle, semidiagrannnatic, 

 xll50 approx. (after Chagas). D-H. Metamorphosis of the leishmanial into 

 the trypanosomal form, semidiagrammatic, x2300 approx. (after Wenyon). 



triatomid bugs — belonging mostly to the genera Panstrongylus, Rhodnius, 

 and Triatoma — have been found naturally infected, the incidence rang- 

 ing from 16 to 92 per cent in different areas. Infected insects have been 

 observed in Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, French 

 Guiana, Guatemala, Honduras, Mexico, Panama, Paraguay, Peru, El 

 Salvador, Uruguay, Venezuela, and also in Arizona, California, and 

 Texas. In the United States, insect infection was first reported for 

 "Trypanosoma triatomae" in Triatoma protracta of California. Subse- 



