STAINING. 



[ 729 ] 



STAINING. 



give a sketch of the 



numerous ; we will 

 priucipal and their uses. 



Among- these are carmine, indigo-carmine, 

 alkaUne sulphindigotates, saiiron, aniline 

 blue, eosiue, I'uchsiuo, magenta, logwood, 

 picric acid, ink, and Judson's dyes. 



Frey recommends that 3 to grains of 

 carmine (better carminic acid ?) be dissolved 

 in a few drops of Liq. Ammon., with an 

 ounce of distilled water. To the filtered 

 liquid is added 1 ounce of glycerine, and 

 2 to 3 drachms of alcohol. This solution 

 may be used alone, diluted with water, or 

 with glycerine. The duration of the mace- 

 ration will vary according to the kind of 

 tissue and the strength of the dye-liquor ; 

 in some cases a few minutes are enough, in 

 others 24 hours are required. The pieces 

 of tissue are then washed with water or a 

 very weak acid (an oimce of distilled water 

 with 2 or 8 drops of acetic acid). Fresh 

 tissues, or those hardened by alcohol are 

 best ; next those previously treated with 

 chromic acid or bichromate of potash. 

 Preparations to be preserved in feebly acidi- 

 fied glycerine require to be less dyed than 

 those to be moimted in balsam. 



Gerlach used a concentrated solution of 

 carmine in ammonia, and placed the sec- 

 tions of brain and spinal cord, previously 

 hardened by solution of chromic acid, in the 

 carmine solution for ten or fifteen minutes. 

 They were then well washed in water and 

 treated with acetic acid ; subsequently the 

 water and acid were removed by absolute 

 alcohol ; and the preparations were then 

 mounted in Canada balsam. Afterwards 

 he found that better results were obtained 

 by using dilute solution of carmine and 

 ammonia — for instance, two or three drops 

 of the ammoniacal solution to an ounce of 

 water. He advised also maceration in this 

 solution for two or three days. Beale's 

 carmine fluid for staining protoplasm is 

 made as follows : — 



Carmine 10 grains. 



Strong liquor ammonite h drachm . 



Price's glycerine 2 oimces. 



Distilled water 2 ounces. 



Alcohol I ounce. 



The carmine in small fragments is to be 

 placed in a test-tube and the ammonia 

 added to it. By agitation and heat the car- 

 mine is soon dissolved ; "then the solution is 

 boiled for a few minutes and allowed to cool. 

 After an hour any excess of ammonia will 

  have escaped ; the glycerine and water 

 may then be added and the whole filtered. 



The clear fluid is to be kept in stoppered 

 bottles ; and should any carmine be preci- 

 pitated, a drop or two of liquor ammonife 

 should be added. Care should be taken 

 that the solution and the tissue to be stained 

 have not too alkaline a reaction; other- 

 wise the staining Avill be too intense, and 

 some of the tissue surrounding the proto- 

 plasm will be destroyed. The permeating 

 power of the fluid is increased by the addi- 

 tion of alcohol and water. This is a most 

 valuable staining agent, but requires care. 

 Thiersch recommends: — carmine 1 part, 

 caustic ammonia sol. 1 part, distilled water 

 3 parts ; the solution is to be filtered ; oxalic 

 acid 1 part, distilled water 22 parts. One 

 part of the carmine solution is to be mixed 

 with 8 parts of the oxalic acid solution, and 

 12 parts of absolute alcohol are to be added. 

 Should the solution turn out orange-co- 

 loured, more ammonia should be added. 



A solution of carmine in borax is some- 

 times used — 4 parts of borax dissolved in 

 50 parts of water, to which is added 1 part 

 of carmine. The filtered solution is mixed 

 with 2 volumes of alcohol. This solution 

 answers well in dyeing cartilage. 



Frey gives the following formula for 

 Thiersch's blue staining fluid : — Oxalic acid 

 1 part, distilled water 22 parts, indigo-car- 

 mine as much as the solution wiU take up. 

 Another solution of oxalic acid and water 

 in the same proportion is required; and one 

 volume of the first solution is mixed with 

 two volumes of the last and nine of absolute 

 alcohol. An aniline-blue solution may be 

 made as follows : — Soluble aniline blue 

 I grain, distilled water 1 oz., alcohol 2odrops. 

 This fluid is not acted on by acids or alkalies. 

 Magenta colours rapidly, and hence it is very 

 useful ; but its eftects are not permanent. 

 Eutherford gives the following formulae : — 

 Crystallized magenta 1 grain, absolute alco- 

 hol 100 minims, distilled water 5 oz. This 

 is used for the tissues generally; and the 

 following is for blood-corpuscles : — Crystal- 

 lized magenta 1 part, rectified spirit 50 

 parts, distilled water 150 parts, glycerine 

 200 parts. 



Very often nerve does not stain readily 

 with carmine after hardenino- in a solution 

 of chromic acid. This maj^ be obviated bv 

 placing the section in absolute alcohol for a 

 short time in order to get rid of the water ; 

 then it is placed in a solution composed of 

 water 300 to 600 parts, and chloride of pal- 

 ladium 1 part. As soon as a pale straw- 

 colour is seen on the section, it may be 



