SPREADING FACTORS 



230 



STARCH GRAINS 



needed for compounds of hyaluronic 

 acid. 



Spreading factors can be measured by 

 comparing the spread of a colored fluid 

 injected intradermally in rabbits to- 

 gether with the factor and in its ab- 

 sence. 

 Sputum. Amount, gross appearance, color 

 and odor (if present) are important. 

 Microscopic examination should first 

 be made mounted but unstained. Look 

 for pus, elastic tissue, pigmented heart 

 failure cells, amebae, fungi, ova of ani- 

 mal parasites, colorless, hexagonal 

 pointed Charcot-Leyden crystals, other 

 crystalline material, etc. Stain smears 

 by methods of Giemsa, Gram and for 

 Acid Fast bacilli. It may be necessary 

 to use Concentration methods. Inter- 

 pretation of findings requires much 

 experience . Comparison of chlorox and 

 sodium-hydroxide-alum techniques for 

 tubercle bacilli in sputum (Cameron, 

 G. M. and Castles, R., J. Lab. & Clin. 

 Med., 1946, 31, 361-368). See also Sec- 

 tion on Sputum Examination in Osgood, 

 E. S., Laboratory Diagnosis. Phil- 

 adelphia: Blakiston Co., 1940, 676 pp. 

 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) possess granules which are homo- 

 logous for the several species but differ 

 in staining reaction for the species 

 (Maximow — 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 fiuids. Stains and smell of 

 putrefaction caused by them can be 

 removed, as above, by permanganate 

 and oxalic acid. 

 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- 



