54 MICRO-CHEMICAL REAGENTS. 



carmine are dissolved ; the former in one hundred 

 parts of water, the latter in fifty parts of concen- 

 trated ammonia. The solutions are then mixed 

 and filtered, evaporated to dryness, and the residue 

 is redissolved in a hundred times its weight of 

 water. 



Protoplasm is colored a yellowish-red by it. The 

 nucleus quickly assumes a deeper color, especially 

 after very short action of the coloring matter. The 

 best degree of concentration is a one per cent, 

 solution. Maupas recommends the use of alcohol, 

 picro-carmine, and glacial acetic acid for staining 

 the nucleus. 1 



[Mayer's picro-carmine 2 is prepared as follows : 

 "To a mixture of powdered carmine (2 g.) with 

 water (25 cc.), while heating over a water-bath, 

 add sufficient ammonia to dissolve the carmine. 

 The solution may then be left open for a few 

 weeks in order that the ammonia may evaporate ; 

 or the evaporation may be accelerated by heating 

 (Hoyer). So long as any ammonia remains large 

 bubbles will form while boiling, but as soon as the 

 free ammonia has been expelled the bubbles will 

 be small, and the color of the fluid begin to be a 

 little lighter. It is then allowed to cool, and fil- 

 tered. To the filtered solution is added a concen- 

 trated aqueous solution of picric acid (about four 



1 Maupas : Comptes rendus, July 1879, No. 4, p. 250. 



2 Mayer: M T. Zool. Stat. Neapel, 1880, II., pp. 1-27. Journ. Roy. 

 Mic. Soc., Dec. 1882, Ser. 2, Vol. II., pp. 876-7. 



