STAINING 



325 



STARCH PASTE 



adelphia: Blakiston Co., 1940, 676 pp. 

 See Papanicolaou Techniques. 



Staining is the act of giving color to some- 

 thing. It is said to be progressive when 

 the structures colored take up the stain 

 progressively to a greater degree than 

 do others which by contrast are not 

 colored. Thus, in testing for iron by 

 the Macallum method the iron is stained 

 progressively with hematoxylin. Stain- 

 ing is called regressive when many 

 structures are over stained and by 

 decolorization, or differentiation, the 

 color regresses and is retained only by 

 those which hold it most tightly in con- 

 trast with which the others are not 

 stained. To demonstrate Nissl bodies 

 in nerve cells the cells are over stained 

 with toluidin blue. By decolorization 

 in alcohol the color is made to regress to 

 the point where the Nissl bodies stand 

 out colored in a cytoplasm no longer 

 blue. See, also vital and supravital 

 staining and acid and basic dyes. 



Acid stains are often contrasted with 

 basic ones though the dyes are usually 

 neutral salts. In "acid" dyes it is the 

 acid part, or anion, that is colored and 

 does the staining; while in "basic" dye 

 the reverse holds and it is the basic por- 

 tion, or cation, that is the coloring agent. 

 For instance, acid fuchsin is a sodium 

 salt of sulphonic acid of fuchsin and it 

 is the acid part which gives the color. 

 Basic fuchsin, on the other hand, is a 

 hydrochloride of rosanilin and it is the 

 base, rosanilin, which stains. A "neu- 

 tral" dye is a more complex association 

 between a color acid and a color base. 



Basic materials may be colored by 

 acid dyes and acid ones by basic dyes, 

 but this does not by any means always 

 hold. A substance staining by an 

 "acid" dye is said to be acidophilic, as 

 for example the specific granules of 

 eosinophile leucocytes which take the 

 "acid" dye eosin. Similarly another 

 material, such as nuclear chromatin is 

 termed basophilic because it colors with 

 toluidin blue which is a "basic" stain. 

 A neutrophilic granule is colored by 

 both the color acid and the color base of 

 a neutral dye. An amphophilic one 

 (G. ampho, both; philos, fond) will 

 stain with either acid or basic dyes or 

 with a neutral dye for it likes both color 

 acids and color bases. Heterophile 

 leucocytes (G. heteros, other, and philos, 

 fond) px)ssess granules which are homo- 

 logous for the several species but dififer 

 in staining reaction for the species 

 (Ma.ximow — Bloom, Histology, 2nd Edit. 

 1934). See Supravital and Vital Stains. 



Stains. The laboratory worker desiring to 

 keep clean can use the methods advised 



by W. C. Tobie (Simmons, and Gentz- 

 kow, p. 358). 



Bacteriological stains on hands. 

 Wash in 2 or 3% cone, hydrochloric acid 

 in 95% alcohol (by vol.) and then in 

 soap and water. For fabrics, wash in 

 10% acetic acid in 95% alcohol (by vol.) 

 and rinse repeatedly in much water; in 

 case stain remains wash with dilute 

 chlorine, or bromine water, or with fil- 

 tered chlorinated lime solution (as 

 "HTH" high test hypochlorite) and 

 rinse again in water. 



Iodine stains. Remove with aq. 

 sodium thiosulphate and wash in water. 



Blood stains. Wash away with 3% 

 aq. hydrogen peroxide, and rinse in 

 water. 



Silver stains occasioned by silver 

 nitrate, argyrol and the like. Treat 

 with hot solution of 5 gm. mercuric 

 chloride + 5 gm. ammonium chloride in 

 100 cc. water. 



Mercurochrome stains. Wash out 

 fresh ones with dilute bromine water or 

 chlorine water or fresh aq. filtered 

 chlorinated lime (HTH). Old ones 

 should be treated with 2% aq. potas- 

 sium permanganate followed by 5% aq. 

 oxalic acid and washing in water. 



Biological fluids. Stains and smell of 

 putrefaction caused by them can be 

 removed, as above, by permanganate 

 and oxalic acid. 

 Standards. See Biological Standards, Nor- 

 mality, Normals. 

 Starch Grains. The usual microchemical 

 test is to color blue with dilute iodine. 

 Starch grains can also be stained side 

 by side with mitochondria in plant cells 

 (Pea roots, Elodea, etc.). After Re- 

 gaud fixation stain sections with warmed 

 anilin fuchsin about 5 min. Differen- 

 tiate in 5% alcoholic aurantia. Wash 

 in aq. dest. Mordant in 2% aq. Tan- 

 nin, 20 min. Wash in aq. dest. and stain 

 in 1% aq. toluidin blue, gentian violet 

 or methyl green, 5-10 min. Milovidov, 

 (P. F., Arch. d'Anat. Micr., 1928, 24, 

 8-18). Differentiate in 95% ale. dehy- 

 drate in abs. ale, clear in xylol and 

 mount. Mitochondria red, starch blue, 

 violet or green. Well shown in an 

 excellent colored plate. Armed with 

 illustrations showing the distinctive 

 structural features of starch granules 

 from many species of plants it is ordi- 

 narily a simple matter by direct micro- 

 scopic examination to identify a given 

 sample of starch (Schneider, A., The 

 Microbiology and Microanalysis of 

 Foods. Philadelphia: P. Blakiston's 

 Son & Co., 1920, 262 pp.). See Poly- 

 saccharides. 

 Starch Paste, as substitute for albumin- 

 glycerin mixture in mounting paraffin 



