PIROPLASMA MURIS. 495 



designate the parasite described in this paper as Piro- 

 plasma muris. 



II. Technique. 



Fresh blood-films, obtained from the tail or ear, were ex- 

 amined from time to time, and in some cases a few red blood- 

 corpuscles exhibited, in their interior, small, bright, usually 

 ovoid bodies with dark contour, which occasionally showed 

 slight motility. The change of position inside the corpuscle 

 was usually from near the periphery towards the centre and 

 back again to the periphery, and it sometimes set up slight 

 rotation of the corpuscle. No especial change of shape was 

 noticed. The small size of the intra-corpuscular or endo- 

 globular bodies increased the difficulty of observation in 

 freshly-drawn blood. 



Most of the observations hereafter recorded were, however, 

 made on fixed and stained preparations of thin smears or films 

 of blood from the peripheral circulation, and on smears made 

 from certain of the internal organs as soon after death, as 

 possible. Many of these were stained for some time with 

 various modifications of the Romanowsky method, especially a 

 combination of the methods of Laveran and Plimmer, using 

 Bleu Borrel, erythrosin, and tannin orange. I also obtained 

 good results with Leishman's stain, which possesses the added 

 advantage of simplicity ; and with an adaptation of Giemsa's 

 stain, using a 1 per cent, aqueous solution of azur ii, together 

 with a O'l per cent, aqueous solution of erythrosin,^ mixed on 

 the slide after fixation with pure methyl alcohol. Leishman's 

 stain is useful in that it imparts to the erythrocyte-cytoplasm 

 a pink coloui-, which affords — quite easily — a contrast with 

 the blue cytoplasm and red chromatin of the enclosed para- 



1 Tlie respective quantities were : — 1 drop of azur ii to 2 drops of ery- 

 throsin, diluted with 5 to 8 drops of distilled water. The preparation may 

 afterwards be stained with a dilute solution of tannin orange. The azur ii 

 may be used first, followed for a short time by erythrosin, with good results. 

 VOL. 50, PART 3. NEW SERIES. 35 ' 



