298 SPOEOZOA. 



249. Theileria mutans (Theiler). (Fig. 145.) 



Piropla»ma mutans, Theiler, 1906, pp. 292-300 ; 1909, pp. 115-33. 

 ■fPiroplasma mutans, Gaiger, 1910, p. 66 ; Baldrey, 1911, p. 569. 

 Piroplasma m,utans, Theiler, 1911, pp. 202-3. 

 Babesia ^nutans, Minchin, 1912, pp. 380, 382. 

 Gonderia tnutans, du Toit, 1918, p. 86, fig. 8. 

 Theileria mutans, Castellani & Chalmers, 1919, p. 499 ; Brumpt, 



1923, pp. 16-53, pis. i, ii ; Velu, 1923, pp. 54r-64, 6 figs. ; Doyle, 



1924, pp. 18-27. 



■fTheileria mutans, Edwards, 1925, pp. 48-9 ; 1926, p. 43 ; Cooper, 

 1926 a, pp. 96-7 ; 1926 b, pp. 315-16, pi. xviii, fig. 2. 

 Babesia mutans, Wenyon, 1926, pp. 1001-2, 1035, fig. 413 ; 



Knowles, 1928, pp. 451, 453, fig. 106. 

 Theileria mutans, Reichehow, 1929, p. 1025, fig. 1012 ; Du Toit, 

 1931, pp. 551-2. 

 ■fTheileria mutans. Cooper, 1931, pi. i, figs. 2, 3 ; Achar, 1935, p. 9. 

 Theileria tnutans, Reichenow, 1935, p. 377. 



Blood-forms and schizonts very similar to those of T. parva. 

 The blood-forms are exceedingly minute, comma-shaped, 

 bacilhform or coccal ; dumbbell-shaped, ring or even cross- 

 shaped forms occur, the largest not exceeding 1 fj, in diameter. 

 Schizonts very similar to Koch's " blue bodies " ; they are 

 larger than those of T. parva, and the nuclei tend to be ovoid 



BCD 



Fig. 145. — Theileria mutans (Theiler). ( x c. 4000.) A-D, different 

 forms in the blood -corpuscles. (From Wenyon, after 

 Gonder. ) 



and not spherical as in the latter. They occur in small 

 numbers in the internal organs as well as in the peripheral 

 blood. 



Transmission occurs by ticks of the genus Bhipicephalus ; 

 ticks fed at the nymphal stage transmitted the infection when 

 feeding as adults. 



Eemarks. — Compared with T. parva, T. mutans is a benign 

 parasite. The infections are mild in character, and the 

 parasite does not cause haemoglobinuria, though it may 

 cause a certain amount of anaemia. Theiler (1906) showed that 

 inoculation of infected blood readily conveys infection to 

 healthy animals, and this was regarded as the chief distinction 

 between T. parva and T. mutans, so much so that cross-forms 

 which occur in both species were differently interpreted, 

 in T. parva as being due to aggregation of four parasites, and 

 in T. mutans as binary fission, and the latter organism was then 



