TRYPANOSOMES OF ANIMALS 



developed undulating membrane. Movements active. Final stage 

 in the definitive host is confined to the proboscis and hypopharynx. 



Type Species. — Bruce's Uganda strain of vivax, which is probably the same 

 as cazalboui. 



Other Species. — The other species may be recognized as follows: — 



[a) Kinetonucleus large and terminal. Undulating membrane 



well developed and simple. Invertebrate host a glossina : — 



1. Rats refractory — Uniformis. 



2. Rats susceptible — Vivax. 



3. Only equidse and ruminants susceptible — Capree. 



(b) Kinetonucleus prominent and subterminal. Undulating 



membrane poorly developed : — 



1. Small, 8-18 microns; found in cattle — Pecorum. 



2. Larger, 14-24 microns; found in monkeys — Simics. 



B. Unclassifiable : — 



Genus Trypanosoma sensu lato : — • 



Group I : Part of the fiagellum always free. 

 Group 2 : No part of the fiagellum free. 

 Group 3 : Part of the fiagellum may or may not be 

 free. 



Group 4: Little-known forms. 



TRYPANOSOMES OF ANIMALS. 

 FORMS. CLASSIFIABLE. 



Genus Casteilanella Chalmers, 1918. 



Castellanella evansi Steel, 1885. 



Synonyms. — Spivochcsta evansi Steel, 1885; H cBmatomonas evansi Crook- 

 shank, 1886; and Trichomonas evansi Crookshank, 1886. According to Yorke 

 and Blacklock, T. soudanense and T. venezuelense ; according to Bruce, 

 T. soudanense Laveran. 



Castellanella evansi, discovered by Evans in India in 1880, is the cause 

 of a disease called surra, which occurs in horses, mules, camels, and cattle in 

 India, Burma, Indo-China, Java, Philippines, Mauritius, and North Africa. 

 With regard to cattle, they were supposed to be immune until the outbreak in 

 Mauritius in 1902, which killed from 25 to 100 per cent, of the infected cattle. 



Morphology. — Thistrypanosome, 25 ^ in length and 1-5 in breadth, has a 

 pointed anterior extremity, a long fiagellum, and is actively motile. It repro- 

 duces asexually by simple division. 



Walker finds that a schizogony takes place in the spleen of the vertebrate 

 host. The trypanosome in the capillary bends round until its two ends meet 

 and fuse, forming a ring, which may become a disc with the fiagellum at first 

 attached, but subsequently lost. These bodies measure 2*5 jj, in diameter, and 

 possess a kinetonucleus and a trophonucleus. They grow, and their nuclei 

 divide until they reach a size of 10 to 1 5 in diameter, and divide into four to 

 sixteen kineto- and tropho-nuclei, and eventually form mesozoites inside a 

 thin cyst wall. Each mesozoite is 6 to 10 fji in length and i to i'5 in width, 

 with two nuclei, but no fiagellum or undulating membrane. These mesozoites 

 are believed to develop into trypanosomes. No dimorphism in these bodies 

 has been seen. 



Life-History. — Holmes recognizes male and female forms, which he considers 

 conjugate by the anterior extremities only, after which the female divides, 

 forming four amoeboid bodies, which, in the liver, spleen, and bone-marrow, 

 develop into trypanosomes. This appears to somewhat resemble the descrip- 

 tions of Breinl and Hindle of latent forms in C. castellanii. C. evansi can be 



