TRYPANOSOMA CRUZI 83 



and Sinton, succeeded in cultivating T. rhodesiense in a modified 

 Novy-MacNeal medium. The development obtained resembled that 

 of the trypanosome in the intestine of Glossina. 



GENERAL NOTE ON TRYPANOSOMES WITH POSTERIOR NUCLEI. 



Posteriorly placed nuclei have been found to occur not only in 

 T. rlwdesiense by Stephens and Fantham (1910), but also in T. pecaudi 

 by Wenyon (1912), in T. brucei by Blacklock (1912), and in T. equi- 

 perdnm by Yorke and Blacklock (1912). 



Recently Stephens and Blacklock (19 13) 1 have shown that two 

 trypanosomes, different morphologically, have been confused under 

 the name T. brucei. One of these is polymorphic (i.e., it exhibits 

 long and slender as well as short and stumpy forms) and came from 

 Uganda, while the other is monomorphic and is the original Zululand 

 strain described by Bruce from cattle suffering from "nagana." Bruce 

 (1914) considers that morphological change has occurred in T. brucei 

 in its passage through laboratory animals, and thus explains the 

 diversity of views. The posterior nuclear forms described by 

 Blacklock occurred in the Uganda strain of T. brucei. (See p. 95.) 

 Similarly, a posterior nuclear form, T. cqui, has been separated from 

 T. eqniperdum. (See p. 98.) 



Again, Bruce and his colleagues on the Royal Society Commis- 

 sion investigating sleeping sickness in Nyasaland, have stated (April, 

 1913) that " evidence is accumulating that T. rhodesiense and T. brucei 

 (Plimmer and Bradford) are identical." The exact identity of trypano- 

 somes showing posterior nuclei is, then, far from settled, although 

 Laveran by cross immunity tests has declared that T. brucei is distinct 

 from T. rhodesiense. No one has yet seen posterior nuclei in T.gambiense. 



Trypanosoma cruzi, Chagas, 1909. 

 Syn. : Schizotrvpanum cruzi, Chagas, 1909. 



The trypanosome was discovered by Chagas 2 in the intestine of 

 the bug, Triatoma (Conorhinus) megista, in Brazil, and then in the 

 blood of a small monkey bitten by the bug. A little later it was found 

 in the blood of a child, aged two years, suffering from irregular fever, 

 extreme anaemia and enlarged glands in the State of Minas Geraes, 

 Brazil. Chagas found that he was able to infect many of the usual 

 laboratory animals with the trypanosome, by allowing the bug to bite 

 them. He was also able to culture the parasite on blood agar. 



Chagas found the Reduviid bug, Triatoma megista, in the houses 

 of the poorer inhabitants of the Brazilian mining State, and that it 

 attacked the people, more especially the children, at night, biting the 

 face. On this account the insect is called " barbeiro " by the 



1 Proc. Roy. Soc., B, Ixxxvi, p. 187. 2 Mem. Inst. Oswaldo Cruz., i, p. 159. 



