350 



PROTOZOOLOGY 



the host animal in from two weeks to a few months; wild animals 

 are equally susceptible; the disease occurs, of course, only in the 

 region in Africa where the tsetse flies live. 



T. theileri Laveran (Fig. 145, b). Large trypanosome which oc- 

 curs in blood of cattle; sharply pointed at both ends; 60-7 0/t long; 

 myonemes are well developed. Cytology (Hartmann and Noller, 

 1918). 



T. americanum Crawley. In American cattle; 17-25/u or longer; 

 only crithidia forms develop in culture. Crawley (1909, 1912) found 

 it in 74 per cent and Glaser (1922a) in 25 per cent of cattle they 

 examined. The latter worker considered that this organism was an 

 intermediate form between Trypanosoma and Crithidia. 



Fig. 145. a, Trypanosoma brucei; b. T. theileri; c, T. melophagium ; 

 d, T. evansi; e, T. equinum; f, T. equiperdum; g, T. lewisi; all X1330 

 (several authors). 



T. melophagium (Flu) (Fig. 145, c). A trypanosome of the sheep; 

 50-60m long with attenuated ends; transmitted by Melophagus 

 ovinus. 



T. evansi (Steel) (Fig. 145, d). In horses, mules, donkeys, cattle, 

 dogs, camels, elephants, etc.; infection in horses seems to be usually 

 fatal and known as "surra"; about 25/x long; monomorphic; trans- 

 mitted by tabanid flies; widely distributed. Transmission (Nieschulz, 

 1928). 



T. equinum Vages (Fig. 145, e). In horses in South America, caus- 

 ing an acute disease known as "mal de Caderas"; other domestic 

 animals do not suffer as much as do horses; 20-25/* long; without 

 blepharoplast. 



