170 CHAPTER XII. 



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 concentrated 

 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, 

 a quality that enables it to be used where ordinary reagents would totally 

 fail. 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 Zeit. 

 f. wiss. Mik., x, 4, 1894, p. 502). Probably for almost all the purposes for 

 which aceto-carmine is useful, methyl-green will give better results. 



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

 1898, p. 232 : Zeit.f. wiss. Mik., xv, 4, p. 453 ; Journ. Roy. Mic. Soc., 1899, 

 p. 453. 



218. Iron Carmine (ZACHARIAS, Zool. Anz., No. 440, 1894, 

 p. 62). Stain for several hours in carmine (Zacharias stains 

 in an aceto-carmine, of which I suppress the formula, for, as 

 pointed out to me by Dr. MAYER, and as I have verified, 

 carmalum does just as well) . Rinse the objects with dilute 

 acetic acid, and bring them (taking care not to touch them 

 with metallic instruments if the aceto-carmine have been 

 taken) into a 1 per cent, solution of ammoniated citrate of 

 iron (the pharmaceutical Ferri et Ammonias Citras}. Leave 

 them till thoroughly penetrated, for as much as two or three 

 hours if need be. In this solution they take on a black tint 

 (with sections this happens in a few minutes). They should 

 be removed as soon as the reaction has taken place through- 

 out, otherwise there is risk of over-blackening. Wash for 

 several hours in distilled water, dehydrate and mount in 

 balsam. 



This is at the same time a chromatin stain and a plasma 

 stain. In my preparations chromatin is blue and plasmatic 

 elements brown. I consider the method may render service 

 in some cases. 



PFEIFFER VON WELLHEIM (Zeit. f. wiss. Mik., xv, 1, 1898, p. 123) 

 mordants for six to twelve hours in a very weak solution of chloride of 

 iron in 50 per cent, alcohol, washes in 50 per cent, alcohol, and stains for a 

 few hours in a dilute solution of carminic acid in 50 per cent, alcohol. 

 Overstains may be corrected with O'l to 0'5 per cent. HC1 alcohol. 



