CARMINE AND ANILIN BLUE. 155 



up in a mortar, allow the fluid to stand some time, decant, filter, and keep 

 in a stoppered bottle. 



(B) Take 8 grms. of indigo-carmine, 8 grms. of borax, and 128 c.c. of water 

 (or two drachms indigo-carmine, two drachms borax, and four ounces water). 

 Mix, decant, filter, and preserve as before. 



Before using, mix A and B in equal proportions. 



The objects to be stained must be thin ; all traces of chromic acid or 

 chromates must have been carefully washed out from them, and they must 

 be soaked in alcohol before staining. Stain for fifteen or twenty minutes 

 (MAX FLESCH finds it better to stain for several hours, see Zeit. f. wiss. 

 Mik.y 1885, p. 350). Wash out with saturated aqueous solution of oxalic 

 acid for a rather shorter time ; wash the acid out with water, and mount as 

 desired. 



The oxalic acid is necessary for fixing the indigo-carmine, which, being 

 .very soluble in water, would otherwise be washed out. Unfortunately it 

 precipitates carmine, so that successful preparations are not easily obtained, 

 the carmine being generally either precipitated or turned into a straw-colour. 



Authors (MEBKEL, loc. cit. ; NOEBIS and SHAKE SPEAEE, Amer. Journ. 

 Med. fife., January, 1877 ; MEBZEL, Mon. Mic. Journ., 1877, p. 242 ; MAESH, 

 Section Cutting, p. 85 ; BAYEEL, Arch. f. mik. Anat., xxiii, 1885, pp. 36, 

 37 ; MACALLUM, Trans. Canad. Instit., ii, 1892, p. 222 ; Journ. Roy. Mic. 

 'Soc., 5, 1892, p. 698) are unanimous in stating that successful preparations 

 show a most richly differentiated and yet very precise colouring. According 

 to Bayerl, the stain is quite specifically elective for red blood-corpuscles, 

 whitfh are^ stained of an apple-green. The ground substance of cartilage and 

 bone stains blue, their cells red. 



The stain is not perfectly permanent. Bayerl recommends that benzin be 

 used for clearing, in lieu of clove oil, which oxidises the stain and injures it. 



This method has recently been recommended for nerve-centres. For 

 Bayerl's application of it to ossifying cartilage see Part II. 

 . I have put this method in small type because, though admirable for certain 

 special purposes, it is not at all to be recommended for general work. 



243. Carmine and Anilin Blue (or Bleu Lumiere, or Bleu de 

 Lyon). DUVAL (Precis de technique microscopique, 1878, p. 225) 

 proceeds as follows: Stain with carmine " in the ordinary 

 .way;" dehydrate, and stain for a few minutes (ten minutes 

 for a section of nerve-centres) in an alcoholic solution of 

 anilin blue (ten drops of saturated solution of anilin blue 

 soluble in alcohol to ten grammes of absolute alcohol, for 

 sections of nerve-centres). Clear with turpentine, without 

 further treatment with alcohol, and mount in balsam. 



The sections should appear of a fine dark violet when taken 

 from the anilin; they are extremely transparent under the 

 microscope nerve-cells and axis-cylinders reddish violet, 

 blood-vessels bluish violet, and so sharply marked out that 



