140 CARMINE AND COCHINEAL STAINS. 



224. Iron Cochineal (SPULER, Encyclopaedic d. mile. Technik, 1903, 

 p. 153, and 1910, p. 240). Stain for forty-eight hours in a stove, in 

 extract of cochineal (made in a highly complicated way), wash with 

 water, put into solution of ferric alum of f per cent, strength for twenty- 

 four hours or more. If the stain is not sufficiently intense, the whole 

 process may be repeated. 



PETER (Zeit. wiss. Mik., xxi, 1904, p. 314) stains material in bulk for 

 forty-eight hours (sections eighteen to twenty-four) in an incubator, in 

 a similar extract, acidified with HC1, treats with iron-alum of 2| per 

 cent, for one hour to one day (sections half to two minutes), then 

 alcohol, xylol. paraffin, or balsam. Chromatin black, protoplasm grey, 

 yolk granules red. 



HANSEN (ibid., xxii, 1905, p. 85) stains sections or entire objects in a 

 solution of 5 to 10 grms. cochineal, 8 grms. ferric alum, 250 c.c. water, 

 and 25 c.c. sulphuric acid of 10 per cent., boiled for fifteen to twenty 

 minutes. 



{3. So-called "Neutral" and Alkaline. 



225. Ammonia-Carmine. Best made by the method of RANVIER. 

 Make a simple solution of carmine in water with a slight excess of 

 ammonia, and expose it to the air in a deep crystallising dish until it is 

 entirely dried up. It should be allowed to putrefy if possible. Dissolve 

 the dry deposit in pure water, and filter. 



VAN WIJHE (Vers. Akad., Amsterdam, viii, Deel, p. 507) takes an old 

 strong solution of carmine in ammonia (or boils carmine with ammonia 

 and peroxide of hydrogen), then precipitates it by adding alcohol to 

 excess, washes the precipitate with alcohol, and dries it. 



226. Soda-Carmine appears to be still used by some for central 

 nervous system (see CUCCATI, Zeit. wiss. Mik., iv, 1887, p. 50). It can 

 be obtained from GTRUBLER & HOLLBORN (Natron- Garmin). 



226a. ORTH'S Lithium-Carmine (see early editions) macerates strongly, 

 and is superfluous. For that of BEST, see Zeit. wiss. Mik., xxiii, 1906, 

 p. 322. 



227. Magnesia-Carmine (MAYER, Zeit. wiss. Mik., xiv, 1897, p. 23). 

 Take 1 grm. carmine, 0-1 grm. magnesia usta, and 50 c.c. distilled 

 water, boil for five minutes, filter, and add 3 drops of forrnol. This 

 is the stock solution. A weak solution may be made by boiling 0-1 grm. 

 carmine for half an hour in 50 c.c. of magnesia water (made by leaving 

 0-1 grm. of magnesia usta in contact with 100 c.c. of spring water for a 

 week with frequent agitation, and decanting when required for use). 

 Said to be less injurious to tissues than the other alkaline carmines. 



22S. As to Picro-Carmine. The term " picro-carmine " is 

 commonly used to denote a whole tribe of solutions in which 

 carmine, ammonia, and picric acid exist uncombined in haphazard 

 proportions. These solutions do not contain a double salt of picric 

 and carminic acid and ammonia, or picro-oarminate of ammonia. 

 They are always alkaline, and frequently injurious to tissues. The 



