XVIII] TRYPANOSOMA CAZALBOUI 335 



called by Roubaud the " intestinal trypanosome form." Under 

 favourable conditions these multiply very rapidly and in seven 

 to nine days invade the whole of the intestine as far as the 

 pharynx. These flies are not infective until the parasites have 

 invaded the proboscis and passed through the Crithidia and 

 Leptomonas phase. These proboscis forms multiply and some 

 reach the hypopharynx, where they assume the " salivary 

 trypanosome form " and are then capable of infecting any 

 susceptible animal. 



REFERENCES. 



Bouet and Roubaud (1910). Bull. Soc. Path. Exot. vol. in. p. 599. 



(1911). Ibid. vol. iv. p. 539. 



Bouffard (1908). Ann. Inst. Pasteur, vol. xxn. p. 15. 

 Cazalbou (1904). Rec. de Med. Veter. vol. LXXXI. p. 615. 

 Laveran (1907). Compt. Rend. Acad. Sci. vol. CXLIV. pp. 243-247. 

 Balfour and Wenyon (1908). Rep. Wellcome Research Lab. Khartoum. 



Souma (T. cazalboui Laveran). 



General account. In 1904, Cazalbou described, from the 

 Upper Niger Territories, a cattle trypanosomiasis known to 

 the natives by the name of Souma. Two years later, Laveran 

 described the trypanosome causing this disease under the name 

 of T. cazalboui, and also gave an account of its biological 

 properties. 



The disease has subsequently been observed in most of the 

 provinces of West Africa south of latitude 17 N., especially 

 along the upper valleys of the Niger and Volta. It is common 

 in Uganda and has also been recorded from the French Congo, 

 Congo Free State and Rhodesia. 



Souma is a very widespread disease affecting cattle, horses, 

 mules, and donkeys ; goats, sheep and antelope are also suscep- 

 tible to the infection, but contrary to the general rule for the 

 group of trypanosomes to which it belongs, dogs, cats, monkeys, 

 pigs, rabbits, guinea-pigs, rats and mice are all refractory, and 

 this constitutes one of the principal means of distinguishing 

 T. cazalboui from allied forms. 



T. vivax and T. uniforme are very closely related to this 



