390 



MICROBIOLOGY 



missible from animal to animal. According to Robertson, 1 

 who distinguished it from P. bovis because of the frequent oc- 

 currence of bacillary forms and the minute size of the parasite, 

 the red blood corpuscles are not diminished in number. The 

 organism was described by Theiler. A similar disease due 

 to a like parasite has ben reported in Tunis. 2 The organisms 

 appear in large numbers in the blood. In the early stages of 

 the disease they appear as rods or in ring forms. Miyajima, 3 

 in his work on the cultivation of trypanosomes, indicates that 

 Piroplasma parvum represents a stage in the life cycle of the 



trypanosome. The work of other 

 observers does not confirm 

 this conclusion. Bettencourt 4 

 changed its genus to Theileri 

 on grounds not considered suffi- 

 cient by Gender 5 on account of 

 the variation in the size of the 

 parasites. It is transmitted by 

 means of a tick (Bhiphicephalus 

 appendiciilatus] and it can not 

 be transmitted by the injection 

 of blood. Recovery, from the 

 disease assures complete im- 

 munity and the animals are not subject to a relapse. This has 

 been taken as an indication that the parasites are destroyed 

 after a certain period. Gonder has made observations on the 

 development of the parasite in the tick. The student of piro- 

 plasmosis will find his article of much interest. 



Fig. 84. Piroplasma parvum. 

 (After Theiler). 



1 Robertson. Jour. Comp. Path, and Therap., Vol. XVII (1904) 

 p. 214. 



2 Ducloux. Compt. rendu de la Soc. de Biol., Vol. LVII (1905 ii) 

 p. 461. 



3 Miyajima. Philippine Jour, of Sci., Manila, cited by Crawley, 

 Bulletin 119, B. A. I. 



* Cited by Gonder. 



5 Gonder. Rept. of the Government Bacteriologist, Pretoria, 

 South Africa, 1909-1910, p. 69. 



