168 PLASMA STAINS 



which is not the case, methyl green being a strongly " basic " 

 colour. Ehrlich explains in a letter to Mayer (see also Ehrlich 

 and Lazarus, Die Ancemie, 1898, p. 26) that it is so called " because 

 in it all the three basic groups of the methyl green are combined 

 with the acid dye-stuffs." A very pretty conundrum ! 



The latest receipt {op. cit., p. 28) is as follows : 



Prepare separately saturated solutions of orange G, Saure- 

 fuchsin, and methyl green, and let them clarify by settling. 

 Then mix, in the order given, using the same measure-glass, 

 13 to 14 c.c. of the orange, 6 to 7 of the Saurefuchsin, 15 of dis- 

 tilled water, 15 of alcohol, 12|- of the methyl green, 10 of alcohol, 

 and 10 of glycerin. After adding the methyl green, shake well, 

 but do not filter. 



The mixture keeps well. Lee found its qualities and defects 

 to be much those of the Ehrlich-Biondi mixture. The stain 

 seems more powerful but less delicate, and the methyl green in 

 it appears to have more resistance to alcohol, so that it is better 

 adapted for ordinary work. 



Mayer (Grundzii^e, Lee and Mayer, p. 197) has simphfied the 

 formula thus : Take 1 g. methyl green, 2 g. orange, 3 g. Saurefuchsin, 

 and dissolve in a mixture of 45 c.c. water, 10 c.c. glycerin, and 20 c.c. 

 alcohol of 90 per cent. 



Morel and Doleris (C. R. Soc. Biol., hv, 1902, p. 1255) mix 1 vol. of 

 the solution with one of 8 per cent, formalin and add 01 per cent, of 

 acetic acid, and state that thus the methyl green is better fixed in the 

 nuclei. 



324. Pianese's Saurefuchsin-malachite Green (from Mijller, Arch. 

 Zellforsch., viii, 1912, p. 4) consists of 0-5 grm. malachite green, 01 grm. 

 Saurefuchsin, and 001 grm. Martius yellow in 150 c.c. water and 50 c.c. 

 alcohol. Stain for twenty-four hours, differentiate with alcohol, con- 

 taining 1 to 2 drops of HCl per 200 c.c. 



325. Picric Acid. Picric acid gives useful plasma stains after 

 carmine and haematoxylin. The modus operandi consists merely 

 in adding picric acid to the alcohols employed for dehydrating 

 the objects. 



Solubility at 26° C, in water 1-18 per cent., in alcohol 8-96 per cent. 



Picric acid has considerable power of washing out other anilin 

 stains ; and in combinations with hydrochloric acid it very greatly 

 enhances the power with which this acid washes out carmine 

 stains. It should, therefore, not be added to the acidulated 

 alcohol taken for differentiating borax-carmine stains, or the like, 

 but only to the neutral alcohol used afterwards. It has the 

 great quality that it can be used for staining entire objects, and is 

 much indicated for such objects as small Arthropods or Nematodes, 

 mounted whole. 



