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.Boy. Mic. Soc., 1899, 

 p. 453. 



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

 p. 62). Stain for several hours in carmine (Zacliarias 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 Ammoniee 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 chromatiu 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 WELLHEISI (Zelt. f. iviss. 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. 



