394 MICROBIOLOGY 



Morphology. In the case of intravenous injection this 

 organism appeared first on the eighteenth day in the red blood 

 corpuscles of the spleen pulp, there usually being but one 

 parasite in a corpuscle. Free forms were seen. The number 

 of infected corpuscles was small, varying from 2 to 4%. 

 Smaller forms were found with the others. 



From the descriptions given it appears that there were 

 several piroplasmoses affecting cattle in the tropics and that 

 many of the diseases caused by them exist as mixed infections. 

 The student is referred to the reports of Dr. Theiler and his 

 co-workers for further details concerning these organisms and 

 their effect upon animals. 



Dschunkowsky and Luhs 4 described a piroplasma in the 

 blood of diseased cattle in Transcaucasia which they believe to 

 be a distinct species. Theiler looks upon it as Anaplasma mar- 

 ginale. 



TRYPANOSOMA. 



History and general characteristics of the genus. The 



genus trypanosoma was introduced by Gruby who described 

 trypanosomes in frogs in 1840. This genus of protozoa was 

 studied at intervals and in various species by different work- 

 ers from 1843 to 1880. Lewis in 1878 described trypanosomes 

 in rats. A little later, Evans described them as the cause of 

 surra among horses and camels in India. In 1894 Bruce dis- 

 covered the trypanosome of nagana among the horses and cat- 

 tle in Zululand. Later, other species were discovered and are 

 believed to be the cause of the disease with which they are 

 associated. It has also been found that these organisms are 

 more or less prevalent in the blood of many healthy domesti- 

 cated and wild mammals, birds and cold blooded animals.* 



* Dschunkowsky and Luhs. Centralbl. f. Bakt., Bd. XXXV 

 (1904) p. 486. Also Eighth International Veterinary Congress, Buda- 

 pest, Vol. Ill (1905). 



* For a summary of the literature and. a detailed list of the dis- 

 coveries concerning trypanosomes in different species of animals and 

 birds the student is referred to the work of Laveran and Mesnil on 

 Trypanosomes and Trypanosomiases. 



