PLASMA STAINS 165 



confounded with basic fuchsin, as seems to have been done by- 

 some writers. 



This dye is highly soluble in water, less so in alcohol. Use a 

 0-5 per cent, solution in water and allow it to act on sections tor 

 a few minutes in the case of easily stainable material, or twenty- 

 four hours or more for chrome-osmium material. The stain is 

 fast to neutral alcohol. It is very sensitive to alkalies, so that 

 overstains can easily be removed by washing for a few minutes 

 in tap-water. Acids strengthen the stain, so that it is frequently 

 useful to treat sections after staining for a few seconds with 

 acidulated water. A good stain should show the cytoplasm, 

 together with nuclear spindles and asters, stained red, and 

 connective tissue strongly brought out. It may be advisable 

 to acidify the staining bath very slightly. Successful stains are 

 admirably sharp. 



320. Pyronin. A basic dye, red, only used in mixtures. 



According to Conn (op. cit.) these are Pyronin G, now difficult to 

 obtain, and Pyronin B, which can be used quite well instead of Pyronin 

 G in Pappenhoim's stain described below. Solubility of Pyronin B at 

 26° C, in water 007 per cent., in alcohol 108 per cent. 



Pappenheim (Arch. Path. Anat., clxvi, 1901, p. 427) takes 2 parts 

 1 per cent, solution of methyl green and 1 part 1 per cent, solution 

 of pyronin, stains sections for five minutes, rinses and differentiates 

 in a solution of resorcin or hydroquinon in absolute alcohol. 

 According to Corti and Ferrara, Mon. zool. Ital., xvi, 1905, 

 p. 319, this mixture generally stains chromatin green and cyto- 

 plasm red, but in Flemming or Hermann material the reverse. 

 It seems to us a coarse plasma stain, but likely to be sometimes 

 useful. 



Uxna's carbol-pyronin-methyl green modification {Enzyk. 

 Mik. Tech., 1910, ii, p. 412 : Lee was indebted for the formula 

 to Dr. Gaudlitz) is as follows : Stain for five to ten minutes at 

 30° to 40° C. in methyl green 0-15 parts, pyronin 0-25, alcohol 

 2-5, glycerin 20, and carbolic acid of 0-5 per cent, to make up 100 

 volumes. Cool rapidly, rinse, dehydrate, and pass through 

 bergamot oil, or xylol or benzol {not clove-oil), into balsam. Brings 

 out bacteria (red) in organic liquids. 



321. Orange G. This is the benzazo-beta-naphthol-disul- 

 phonate of soda. As indicated by its chemical description, this 

 is an " acid " colour. 



Solubility at 26° C, in water 10-86 per cent., in alcohol 0-22 

 per cent. 



It is easily soluble in water, less so in alcohol. Use as directed 

 for Saurefuchsin. Almost, if not quite, as precise a stain as 

 Saurefuchsin. It does not overstain, but may wash out other 

 dyes. 



