35O TRYPANOSOMA NANUM [CH. 



host for T. nanum. Laboratory bred flies were fed on an 

 infected sheep and subsequently on a calf, which developed 

 a typical infection with this trypanosome. About five per cent, 

 of the flies fed on this sheep were found to be infected. 



Kleine and Fischer are of the opinion that Glossina morsitans 

 is the intermediate host of T. nanum in the region of Lake 

 Tanganyika. 



Development of the parasite. In the blood the trypanosome 

 multiplies in the usual manner by means of longitudinal division. 



When taken into the gut of G. palpalis the resulting changes 

 are exactly comparable with those that take place in the case 

 of T. gambiense, described above. The trypanosomes begin to 

 develop in the hinder intestine and by the loth day numerous 

 parasites may be found in the hinder and middle intestine. 

 The slender forms begin to be produced from the loth to the 

 I4th day onwards, and the proventriculus is usually invaded 

 about the 20th day. The proventricular forms are not quite 

 so uniformly slender as in the case of T. gambiense. Moreover, 

 there are no marked changes in the appearance of the nuclei 

 of T. nanum. About the 25th day the trypanosomes invade 

 the proboscis, where they may be found attached to the labrum, 

 often lying in clusters. They then pass through the Crithidial 

 phase, many of them being extremely long and slender. 

 Subsequently trypanosome forms are produced which may be 

 found free, sometimes in the hypopharynx and at other times 

 in the labrum. 



The salivary glands never become infected in the case of 

 T. nanum, the proboscis infection apparently playing the same 

 part as the gland infection in the cycle of T. gambiense. 



LITERATURE. 



Laveran, A. (1905). Compt. Rend. Soc. Biol. vol. LVII. p. 292. 



Balfour, A. (1904). B. M. J. Nov. 26, 1904. 



Bruce, Hamerton, Bateman and Mackie (1910). Proc. Roy. Soc. 1910, 



B, vol. LXXXIII. p. 180. 



Duke, H. L. (1912). Proc. Roy. Soc. B, vol. LXXXV. p. 4. 

 Kleine and Fischer (1911). Zeitschr. f. Hyg. u. Infectionskr. vol. LXX. 



p. 18. 

 Robertson, M. (1913). Phil. Trans. Roy. Soc. B, vol. ccin. p. 161. 



