138 CARMINE AND COCHINEAL STAINS. 



200 c.c. Dissolve with heat (if necessary). Decant or filter. Add 

 some antiseptic, either 1 c.c. formol, or 0-1 per cent, salicylic acid, 

 or 0-5 per cent, salicylate of soda. The solution will then keep. It 

 stains well in bulk, even osmium objects. If washed out with 

 distilled water only, the plasma will remain somewhat stained. If 

 this be not desired, wash out carefully with alum solution, or, in 

 difficult cases with weak acid, followed in either case with water. 

 The general effect is that of an alum-carrnine stain. 



A weaker solution may be made by taking from three to five times as 

 much alum and five times as much water, and dissolving in the cold. 



With either solution the objects to be stained should not have an 

 alkaline reaction. 



RAWITZ (Anat. Anz., xv, 1899, p. 438) takes 2 grms. carminic acid, 20 

 grms. ammonia-alum, 150 c.c. water, and 150 c.c. glycerin. A strongly 

 staining solution, which is said to keep well. Only for sections. 



All solutions prepared with alum tend to precipitate. Carmalum 

 made up with 500 c.c. of water instead of 200, and with glycerin or 10 

 per cent, of formol or pyroligneous acid added, keeps well. 



220. MAYER'S Aqueous Aluminium-Chloride Solution (Mittli. Zool. 

 Stat. Neapel, x, 1902, p. 490). Carminic acid, 1 grm. ; chloride of 

 aluminium, 3 grms. ; water, 200 c.c. Add an antiseptic, as for 

 car m alum. 



Use as carmalum. The stain is of a blue-violet colour, very powerful, 

 and elective, but not so purely nuclear as carmalum. It is recom- 

 mended only as a substitute for carmalum in cases in which the latter is 

 counter-indicated on account of the alum in it or the like. 



221. Alum-Carmine and Picric Acid. Alum-carmine objects may 

 be double-stained with picric acid. LEGAL (Morpli\ Jahrb., viii, 

 p. 353) combines the two stains by mixing 10 vols. of alum-carmine 

 with 1 of saturated picric acid solution. I find this very recommend- 

 able. 



Aceto-Carmine (Acetic Acid Carmine) SCHNEIDER (Zool. Anzeig., 

 1880, p. 254). To boiling acetic acid of 45 per cent, strength add 

 carmine until no more will dissolve, and filter. (Forty-five per cent, 

 acetic acid is, according to Schneider, the strength that dissolves the 

 largest proportion of carmine.) 



To use the solution you may either dilute it to 1 per cent, strength, 

 and use the dilute solution for slow staining ; or a drop of the concen- 

 trated solution may be added to a fresh preparation under the cover- 

 glass. If you use the concentrated solution it fixes and stains at the 

 same time, and hence may render service for the study of fresh objects. 

 It is very penetrating. The stain is a pure nuclear one. Unfortunately 

 the preparations cannot be preserved, and for this and other reasons 

 the stain is of very restricted 'applicability. 



