PIROPLASMA MCJRIS. 497 



parasites were more numerous. They were most plentiful in 

 red corpuscles occurring in the capillaries of these organs, as 

 seen in sections, especially in the kidneys, liver, and spleen 

 (fig. 23, dilated capillary of liver). 



Extra-corpuscular stages of the parasite, free in the blood- 

 plasma, occurred in groups, probably resulting from the dis- 

 integration of the corpuscle host (fig. 21). Such groups were 

 noticed sometimes in the peripheral circulation, more fre- 

 quently in spleen blood. 



Leucocytes were relatively rather more numerous than 

 usual in the smears above mentioned, especially in those 

 taken from the sores on the ears. 



IV. Morphology of the Parasite. 



In the red-blood corpuscles of the maminalian host ovoid 

 or pear-shaped organisms ^ were noticed, which, after ade- 

 quate staining by modifications of the Romano wsky method, 

 showed a definite contour, blue cytoplasm, and a red or 

 purple chromatin body, without any trace of pigment. Such 

 characters are diagnostic of the genus Piroplasma. 



These endoglobular bodies may be centrally placed in the 

 blood- corpuscle, but more usually they are rather peripheral 

 in position. They represent the trophozoite stage of the 

 parasite, and may occur either singly (figs. 1 to 3) or in 

 pairs (figs. 6 to 9) within the erythrocytes. Double, and 

 even multiple, infection may be observed, as a dividing 

 trophozoite together with a single pyriform trophozoite, or 

 two trophozoites each in process of division (fig. 10), may 

 be seen simultaneously inside blood corpuscles. In the 

 smaller, and apparently younger forms, the internal chro- 

 matin body is somewhat flattened and peripheral in position 

 (fig. 1). The chromatin body ("nucleus" or "karyosome" 

 of various authors) is, indeed, seldom quite central in posi- 



* The chromation of the parasite stains purple with azur ii alone ; this is 

 a test for a parasite (cf. Koch and Theiler), in coutra-distinction from an 

 artefact. 



