364 CHAPTER XXX. 



28 of acetone, and for staining mix equal parts of these and 

 stain for half a minute to ten minutes. 



JENNER (Lancet, 1899, No. 6, p. 370) mixes equal parts of 

 1*2 to 1*25 per cent, water-soluble eosin (Griibler's) and 

 1 per cent, methylen blue, filters after twenty-four hours, 

 washes the precipitate on the filter, dries it, and dissolves it 

 in 200 parts of absolute methyl alcohol (the solution can be 

 had ready made from Griibler & Hollborn). (Or, simply 

 mix 125 c.c. of 0'5 per cent, solution of the eosin in methyl 

 alcohol with 100 c.c. of 0'5 per cent, solution of methylen 

 blue.) Cover-glass films are floated on to this, in which they 

 are fixed and stained in three minutes. Wash off the stain 

 with a little water (not under the tap), dry, and mount in 

 balsam. Erythrocytes red, all nuclei blue, parasites blue, 

 but with unstained nuclei. 



The methods of MAY and GRUNWALD are closely similar 

 to this. 



ASSMANN (Munch, med. Wochenschr., 190l>, No. 28 ; " Das 

 eosinsaure Methylenblau," Leipzig, 1908, p. 35) treats fresh 

 films for half a minute to three minutes in a Petri dish with 

 a few drops of Jenner's solution (from Griibler & Hollborn), 

 then pours on 20 c.c. of distilled water with five drops of 

 j 1 ^- per cent, solution of lithium carbonate, leaves for five 

 minutes, rinses in distilled water, dries with blotting paper, 

 and mounts in neutral balsam. 



The foregoing mixtures give a stain seemingly due to 

 the formation of an eosinate of methylen blue in which the 

 nuclei of blood-cells are blue and their plasma red to violet. 

 It was made out by ROMANOWSKY (St. Petersburger med. 

 Wochenschr., 1891) that under certain conditions mixtures of 

 these two dyes give a stain which is in some respects the 

 inverse of this, blood-cells being stained in divers hues, 

 according to their kinds, and any protozoan parasites that 

 may be present showing red nuclei and Hue plasma ; which 

 greatly facilitates their detection and diagnosis. This re- 

 action appears to be due to the formation of an eosinate 

 not of methylen blue, but of Methylenazur, 377. The 

 method, only vaguely indicated by Romanowsky, has under- 

 gone, at the hands of ZIEMANN, ZETTNOW, NOCHT, REUTER, 

 MICHAELIS, RUGE, MAURER, IRISHMAN, GiuMSA and others, 

 numerous modifications which have culminated in the 



