348 TRYPANOSOMA NANUM ■ [CH. 



noted that there were a few pre-existing cases of infection in 

 the herd. Afterwards a few Glossina palpalis were found at 

 the foot of the hill. 



Nevertheless, although this circumstantial evidence is so 

 strong, all attempts to transmit the disease experimentally by 

 the bites of either Tabanids or Stomoxys have given uniformly 

 negative results. 



Development within the intermediate host. The development 

 of T. pecorum within the alimentary canal of Glossina palpalis 

 in all essential features resembles that of T. nanum, but is 

 excessively slow, so that it seems probable that this species of 

 tsetse only exceptionally serves as its intermediate host. 



The parasites develop in the hinder intestine and give rise 

 to a large number of trypanosomes of very varying size. 

 Eventually, the slender forms are produced and these are 

 extraordinarily attenuated ; in addition the nuclear changes 

 occurring at this stage in the cycle of T . gambiense, also take 

 place in T. pecorum. The invasion of the proventriculus usually 

 occurs about the 45th day and no proboscis infection was found 

 before the 76th day. The Crithidial phase is passed through in 

 the proboscis, as in the case of T. nanum, and the salivary 

 glands are never invaded. 



LITERATURE. 

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



vol. LXXXII. p. 468. 

 Duke, H. L. (1912). Proc. Roy. Soc. B, vol. lxxxv. p. 554, 

 Kinghorn, A. and Yorke, W. (1912). Ann. Trop. Med. and Parasit. 



vol. VI. pp. 301 and 317. 

 Laveran, A. (1910). Bull. Soc. Path. Exot. vol. iii. p. 718. 

 Robertson, M. (1913). Trans. Roy. Soc. B, vol. cciii. pp. 161-184. 



Trypanosoma nanum Laveran, 1905. 



General account. This parasite was first discovered by 

 A. Balfour in 1904, in the blood of cattle from the Anglo- 

 Egyptian Sudan. It has since been recorded from various 

 other locahties of this region and also in Uganda, where Bruce 

 and his collaborators found it in the blood of cattle. 



