CARMINE AND COCHINEAL 145 



four hours. Rinse in aq. dest. or 30 per cent, alcohol ; immerse 

 in 3 per cent, iron alum solution, in which the sections become 

 black, and are then slowly decolorised ; when differentiation is 

 complete, rinse in a 1 per cent, pyridin solution, and wash under 

 the tap for ten to fifteen minutes. Counterstain and mount as 

 desired. This is a very intense stain suitable for mitochondria 

 and cell granules. See also § 229. 



260. Iron Carmalum (de Groot, Zeit. wiss. Mik., xx, 1903, p. 21). 

 Dissolve 0-1 grm. of ferric alum in 20 c.c. distilled water and add 1 grm. 

 carminic acid. Dissolve, add 180 c.c. of water, warm, add 5 grm. 

 potash alum, dissolve, cool, filter, and add 2 drops of hydrochloric 

 acid. To be used as carmalum, and said to give a stronger stain. 



261. Iron Cochineal (Spuler, Encyclopcedie d. mik. Technik, 1903, 

 p. 153, and 1910, p. 240). Stain for forty-eight hours in an incubator in 

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

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

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

 process may be repeated. 



Peter (Zeit. zviss. 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 HCl, treats with iron-alum of 2J 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 grm. cochineal, 8 grm. ferric alum, 250 c.c. water, 

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

 minutes. 



^. So-called "Neutral" and Alkaline 



262. 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. 



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

 nervous system (see Cuccati, Zeit. iviss. Mik., iv, 1887, p. 50). It can 

 be obtained from Grublp:r & Hollborn (Natron-Carmin). 



264. Orth's Lithium-Carmine (see early editions) macerates strongly, 

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

 p. 322. 



265. Magnesia-Carmine (Mayer, Zeit. wiss. Mik., xiv, 1897, p. 23). 

 Take 1 grm. carmine, 01 grm. magnesia usta (freshly burnt), and 50 c.c. 

 distilled water, boil for five minutes, filter, and add 3 drops of formol. 

 This is the stock solution. A weak solution may be made by boiling 01 

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

 leaving 01 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. 



