39* 



MICROBIOLOGY 



puscles and at times in living parasites. We have not obtained 

 any conclusive evidence that the parasites multiply within the 

 infected corpuscles, but at times appearances were observed 

 suggesting this possibility. In several cases the parasites 

 seemed to grow slightly in size during the period of observa- 

 tion. When infected corpuscles lost their haemoglobin the 

 parasites were distinctly seen for a time, after which they de- 

 generated and died. The escape of parasites from infected 

 corpuscles was witnessed on six occasions ; it was accomplished 

 without injury to the corpuscle. On two occasions the escaped 

 parasites appeared to reenter fresh corpuscles." 



PIROPLASMA MUTANS THEILER 



Synonyms. Babesia mutans. 



Place in nature. This piroplasma was discovered by 



Theiler. 1 It was found in a dis- 

 ease (gall sickness) of cattle in 

 South Africa and often associat- 

 ed with other species of the same 

 genus, especially P. parvum. 

 Theiler found that this disease 

 had a period of incubation in 

 cattle varying from 13 to 42 

 days. Animals immune to P. 

 bigeminum are susceptible to 

 P. mutans. Likewise P. mutans 

 does not protect against P. bige- 

 minum. In earlier work this spe- 

 cies has apparently been confused with other piroplasmae. It 

 exists in South Africa and Madagascar.* 



1 Theiler. Jour. Comp. Path, and Therap., Vol. XIX (1906) p 

 292; Vol. XX (1907) p. 1; Vol'. XXII (1909) p. 115. 



* It corresponds to the species described by Holmes in the Indian 

 hill cattle at Muktesar; Stephens and Christophers in Madras; Mi- 

 Yajuma and Shibayama in Japan; Shein in Annam; Bettencourt in 

 a deer in Portugal; Boevet on the Gold Coast of Africa; Martini in 

 Peychile, in China; Lichtenheld in German East Africa; and Bal- 

 four in the Sudan. 



Fig. 85. Piroplasma mu- 

 tans (after Theiler). 



