486 FAMILY: TRYPANOSOMID^ 



tapering. It was longer than the diameter of the corpuscle, and either 

 pushed this out at one point or was curved to adapt itself to the space 

 available. In the stained films it consisted of blue staining cytoplasm, 

 and possessed a large, round, red nucleus, by the side of which was a rod- 

 like body. As a trypanosome occurred in the blood at the same time, the 

 possibility of these bodies being intracorpuscular stages of the trypano- 

 some naturally occurred to the observers. The parasite did not possess a 

 fiagellum, and no axoneme was visible. It measured 8 to 11 microns in 

 length by 2-5 to 4 microns in breadth. No free forms were discovered, 

 and there did not occur any which could be considered as intermediate 

 between the trypanosomes and the intracorpuscular parasites. 



This curious organism was again seen by Darling (1914) in Panama. 

 He had an opportunity of studying it in the living condition. The 

 parasite was within the red cells immediately after the blood was taken. 

 It showed active movements, and eventually liberated itself from the cell. 

 One end was rounded and the other tapering, and in some there was a 

 definite undulating membrane extending towards the pointed extremity. 

 In stained specimens the nucleus and kinetoplast described by Mesnil 

 and Brimont were seen, and in addition a filament running along one side 

 of the organism. This was undoubtedly the axoneme. The general 

 appearance of the parasite was that of a crithidia or cultural form of a 

 trypanosome, to which it seems to be nearly related. Labernadie and 

 Hubac (1923) also discovered the organism in Guiana. They noted both 

 intracellular as well as free forms. In some there was a free fiagellum 

 4 to 6 microns in length, while occasionally the kinetoplast was at the 

 posterior end of the organism, giving the parasites a definite trypanosome 

 structure. The organism was seen by the writer and Scott (1925.7) in 

 Brazilian sloths (C. didactylus) which had died in London. 



II. THE TRYPANOSOME OF MAN IN SOUTH AMERICA. 



Trypanosoma cruzi Chagas, 1909. — Synonyms: Schizotrypanum criizi 

 (Chagas, 1909); T. escomeli Yorke, 1920. This trypanosome, which pro- 

 duces a disease in man in South America, will be considered here, as it 

 appears to be more nearly related to T. lewisi than to the other pathogenic 

 trypanosomes of man and animals (Plate V., l, p. 456). 



T. cruzi was first discovered by Chagas in 1907, and described by him 

 (1909) as a parasite of the reduviid bug, Triatoma tnegista. The bugs 

 were known to attack man in certain parts of Brazil, and Chagas discovered 

 crithidia forms of a flagellate in the hind-gut of specimens of the bug 

 collected at Minas. Some of these were allowed to feed on a marmoset, 

 Hapale penicillata, which three weeks later showed trypanosomes in its 



