PIROPLASMOSIS 637 



infantum. These facts, however, might be consistent with the 

 existence of three species. 



Histoplasma Capsulatum. Under this name, Darling has described a 

 parasite observed by him in Panama, in certain cases characterised 

 during life by continued irregular fever, spleno-megaly, emaciation, and 

 ana-mia, and post mortem showing minute granulomata in the lungs, 

 irregular necrosis and cirrhosis of the liver, the spleen, naked-eye, 

 resembling that of spleno-mvelogenous leukemia. In smears from the 

 lung nodules, the liver, and spleen, stained by Irishman's method, 

 there were observed enormous numbers of small bodies sometimes crowd- 

 ing endothelial cells, often free. These bodies were round or oval and 

 from 1 to 4 /x in diameter. Each contained an irregularly placed 

 chromatin mass, the shape of which was globular, oval or kidney-shaped, 

 the remainder of the parasite consisting of bine-staining basophilic 

 substance. The parasite is surrounded by a non-staining refractile 

 capsule, one-sixth of the diameter of the parasite in width and sometimes 

 containing a single minute chromatoid dot, and similar granules are 

 sometimes seen in the non-chromatoid part of the body of the parasite. 

 Darling considers this organism to be different from the Leishmania 

 donovani in the form and arrangement of its chromatin and in not 

 possessing a blepharoplast. 



PlKOI'LASMOSIS. 



Up to the present no human disease has been proved to be associated 

 with the presence of piroplasmata. The observations of Donovan, 

 which seemed to indicate that the parasite of kala-azar might be found 

 within the red blood corpuscles, and which led Laveran to denominate 

 the Leishmania donovani the piroplasma donovani, have, as already 

 indicated, not been confirmed ; the same is true of the association of 

 piroplasms with the occurrence of the Rocky Mountain spotted fever 

 sometimes prevalent in Montana. But several important diseases of the 

 lower animals are almost certainly caused by protozoan parasites of this 

 group, and a short account of the organisms may be given. 



The piroplasmata are pear-shaped unicellular organisms about 1 to 1 '5 /* 

 long and varying in breadth. The peripheral part is denser than the 

 central, whicl'i often appears as if vacuolated, and at the broad end there 

 is ;i well-staining chromatin mass. Sometimes irregular and ring-, rod-, 

 or oval-shaped individuals occur. The organisms are found within the 

 red Mood corpuscles of the infected animal and also free in the blood. In 

 the former situation there is sometimes only one within a cell, but the 

 numbers vary under different circumstances and in different species. 

 Multiplication takes place by fission, and the new individuals, remaining 

 fui longer or shorter times in apposition, account for some of the appear- 

 noea seen in cells. Especially in the forms free in the blood pseudopodial 

 prolongations of the protoplasm, usually from the. pointed end, arc 

 developed, and it may be by means of such pseudopodia that entrance to 

 the red cells is obtained. Infection fs usually carried from infected 

 unimals by means'of ticks. In one case Koch has described the develop- 

 ment in the organism, in the stomach of the tick, of spiked protoplasmic 

 processes sprouting out from the broad end of the piro plasm, and the 

 occurrence of conjugation of two such individuals by their narrow ends 

 to form a xygote. Further observations, however, here are necessary, 



