FLAGELLATES ALLIED TO T. CRUZI 497 



mental forms of T. cruzi in the intestine of Triatoma megista. T. geni- 

 culata lives in the burrows of the armadillo {Dasypus novemcinctus), which 

 is commonly infected with a trypanosome. Both this trypanosome and 

 the flagellate of the bug were inoculable to guinea-pigs. The trypanosome 

 which appeared in each case resembled T. cruzi, and Chagas concluded that 

 the armadillo was a reservoir host. Torres (1915) showed that in the 

 endemic centres of the disease three species of armadillo (D. novemcinc- 

 tus, D. sexcinctus, and D. unicinctus) were often naturally infected with 

 T. cruzi. In the burrows in which these animals lived, a reduviid bug, 

 Triatoma geniculata, fed upon them. Chagas (1918) found that as many 

 as 46 to 50 per cent, of armadillos {D. novemcinctus) harboured the try- 

 panosome, as did also the bugs, T. megista, living in their burrows. The 

 armadillos were frequently found infected far from human habitations. 

 It would appear, therefore, that the armadillo is the natural host of a 

 trypanosome which occasionally infects man. Crowell (1923) examined 

 the organs of a naturally infected armadillo captured in Brazil, and found 

 the usual developmental form of T. cruzi in the muscle fibres of the heart. 

 A cat was found by Chagas (1909) to be naturally infected. Chagas (1924) 

 has found that in Brazil in the Para district monkeys {Chrysothrix sciureus) 

 may be naturally infected with T. cruzi. The trypanosome was inoculable 

 to guinea-pigs and young dogs. The latter animals died of the infection, 

 and were found to have the characteristic reproduction forms in the 

 heart muscles. 



OTHER FLAGELLATES RELATED TO TRYPANOSOMA CRUZI. 



It is probable that certain flagellates which have been found in the 

 gut of blood-sucking reduviid bugs are closely related to T. cruzi. Thus, 

 Lafont (1912) described a form seen by him in the gut of Triatoma 

 rubrofasciata in Mauritius. In the gut of the bug there occurred trypano- 

 some, crithidia, and leishmania forms, which resemble very closely the 

 stages of T. cruzi in its invertebrate host. Encysted leishmania forms were 

 also described as occurring in the rectum, but from the figures given there 

 is no evidence that a cyst wall actually exists. It is of interest to note that 

 Lafont was able to infect mice by intraperitoneal injection of the gut 

 contents of the bug. Trypanosomes appeared in the blood of the mice, 

 and remained there up to a maximum of eight days. A transitory 

 infection was also produced in the rat and the monkey {Macacus cijno- 

 molgus). It seems probable that this flagellate, which Lafont named 

 T. boylei, will be found to be a trypanosome of some vertebrate. Cri- 

 thidia conorhincB, described by Donovan (1909a) from Triatoma rubro- 

 fasciata in India, is also possibly a vertebrate trypanosome. The same 

 I. ^2 



