PROTOZOA 393 



The essential lesion caused by P. mutans is anemia with 

 poikilocytosis. According to Theiler, it does not as a rule pro- 

 duce fatal results. It is not, according to the same author, 

 transmitted by the blue tick (Margoropus annulatus}. 



Morphology. P. mutans is very similar to P. parvum in 

 its morphology. 



ANAPLASMA MARGINALE THEILER. 



Place in nature. Theiler has differentiated from Piro- 

 plasma bigeminum, P. parvum and P. mutans, a fourth para- 

 site which he designates Anaplasma marginale, the parasitic 

 nature of which still requires further investigation. Accord- 

 ing to Theiler, A. marginale, hitherto known as "marginal 

 points," causes a severe anemia frequently ending in death. 

 He also holds anaplasma to be an organism reduced by para- 

 sitism, having lost its "originelles" and its plasma so that 

 phylogenitically it represents one of the oldest piroplasmatae. 

 This also needs further elucidation. According to Theiler 1 

 this organism is the cause of "gall-sickness," a type of disease 

 in cattle which is rarely observed spontaneously in a pure state 

 but more commonly occurs as a mixed infection with other 

 piroplasma and possibly trypanosomes. The period of incu- 

 bation is shorter (from 16 to 40 days) after an experimental 

 injection of blood containing the parasite than after a spon- 

 taneous infection (which varies from 60 to 80 days). It is 

 transmitted by the tick Boophilus decolor at us. According to 

 Sieber 2 there can be little doubt of the parasitic nature of 

 these bodies. Theiler 3 points out that it is identical with the 

 coccus-like forms of Piroplasma bigeminum described by 

 Smith and Kilborne and states that anaplasmosis is undoubt- 

 edly identical with .the South African gall sickness. 



1 Theiler. Dept. of Govt. Bacteriologist, Transvaal, 1908-09; 

 Jour. Comp. Path, and Therap., Vol. XXIII (1910) p. 98. 



2 Sieber. The Govt. Vet. Bacteriologist, Report, 1909-10, Pretoria, 

 p. 104. Also 1911, p. 104. 



3 Theiler. Zeit. f. Infektionskrankheiten u. Hyg. der Haustiere, 

 Bd. VIII (1910) p. 39. 



