OARMtNE AND COCHINEAL STAINS. 145 



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

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

 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. 



219. Alum- Carmine and Picric Acid. Alum-carmine objects 

 may be double- stained with picric acid. LEGAL (Morph. 

 Jahrb.j viii, p. 353) combines the two stains by mixing ten 

 vols. of alum carmine with one of saturated picric acid 

 solution. I find this very recommendable. 



219a. 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 mav 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. 



A similar stain has been prepared with formic acid by PIANESE (see 

 Zcit. wiss. Mih., x, 4, 1894, p. 502). 



For BURCHARDT'S pyroligneous-acid carmines see Arch. mik. Anat., 

 liii, 1898, p. 232 ; and Jena. Zeit. Naturw., xxxiv, 1900, p. 720. 



220. Iron Carmine. I recommend trial of the following, 

 which I have already published in the Traite des Meth. 

 Tecliniques, LEE efc HENNEGUY, 1902. Sections (I have not 

 tried material in bulk) are mordanted (a few hours will 

 suffice) in sulphate of iron (Benda's Liquor ferri, as for iron 

 hematoxylin), washed, and stained for an hour or so in 0*5 

 per cent, solution of carminic acid in alcohol of 50 per cent. 

 Wash in alcohol of 50 per cent. ; no differentiation is 

 necessary. When successful, an almost pure chromatin 

 stain, quite as sharp as iron hasmatoxylin, but somewhat 

 weak. 



221. Iron Carmine. PFEIFFER VON WELLHEIM (Zeit. 'wiss. 

 xv, 1898, p. 123) mordants for six to twelve hours in a very weak solu- 

 tion of chloride of iron in 50 per cent, alcohol, washes in 50 per cent. 

 alcohol, and stains as above. Overstains may be corrected with O'l to 

 0*5 per cent. HC1 alcohol. I find this good, but not so good as the last. 



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