384 



SPECIFIC MICRO-ORGANISMS 



Other species of animals are not readily infected. Immunity 

 follows recovery. Artificial immunity has been produced by 

 Novy, Perkins and Chambers 1 by the injection of a pure culture 

 which had been propagated for six years on artificial media and 

 had lost its virulence. 



There are many other relatively harmless trypanosomes 

 parasitic in the blood of various mammals. 



Trypanosoma Brucei. Bruce in 1895 discovered this organism 



D 



FIG. 153. The most important trypanosomes parasitic in vertebrates. A, 

 Tr.kwisi; B, Tr. eiansi (India); C, Tr. evansi (Mauritius); D, Tr. brucei; E, Tr. 

 equiperdum; F, Tr. equinium; G, Tr. dimorphon; H, Tr. gambiense. All magnified 

 (From Do flein after Novy.} 



in the blood of horses suffering from Nagana, the Tsetse-fly dis- 

 ease of Zululand. Pure cultures have been obtained in the con- 

 densation fluid of inclined blood-agar by Novy and MacNeal 

 and the injection of pure cultures into animals produces the dis- 

 ease and death. 



Tr. brucei is 1.5 to 5ju wide and 25 to 35/z long, including the 



1 Journ. Inf. Dis. y 1912, Vol. XI, pp. 411-426. 



