TECHNIQUES 



A-V Bundle, see Todd, T. W., Cowdry's 

 Special Cytology, 1932, 2, 1173-1210. 



Absorption. Every solid surface attracts 

 other substances more or less. This 

 holding is referred to as absorption. 

 The finer the structure of the solid the 

 greater the combined surface area of 

 the constituent particles and conse- 

 quently the greater the degree of ab- 

 sorption. An interferometer is an in- 

 strument employed to measure change 

 in concentration by absorption. There 

 are many other ways of obtaining this 

 information. See Water Absorption and 

 fat absorption after previous coloration 

 of fat with Sudan III or Sudan black 

 (see Vital Staining). 



Absorption Spectra. Methods are avail- 

 able for the determination of absorption 

 spectra of cell structures. Caspersson 

 (T., J. Roy. Micr. Soc, 1940, 60, 8-25) 

 has described apparatus for absorption 

 from intracellular objects larger than 

 1 micron such as Nissl bodies. This 

 line of investigation is just developing 

 and is likely to be productive of im- 

 portant results. See Histospectroscopy. 



Acacia, properties as a macromolecule 

 (Hueper, W. C, Arch. Path., 1942, 33, 

 267-290). 



Acanthocephala, see Parasites. 



Acarina, see Parasites, Ticks. 



Acetic Acid (L. acetum, vinegar). Widely 

 used as a component of fixatives. The 

 undiluted solution is often termed 

 "glacial acetic acid." This contains 

 99.5% CH3COOH. Causes a distinctive 

 swelling of fresh collagenic fibers. 

 Employed in dilute solution to destroy 

 red blood cells so that whites can be 

 examined. In 1% solution separates 

 epidermis from dermis. See Epidermis. 



Acetic-Osmic-Bichromate fixative of Bens- 

 ley. 2% osmic acid, 2 cc; 2.5% aq. 

 potassium bichromate, 8 cc; glacial 

 acetic acid, 1 drop. Excellent for 

 mitochondria but very small pieces of 

 tissue must be used because the fluid 

 penetrates poorly. The best stain is 

 Anilin-Fuchsin Methyl Green, see also 

 Copper Chrome Hematoxylin. 



Acetin Blue R (CI, 560)— Induline Alcohol 

 Soluble — a basic dye of light fastness 4. 

 Paraffin sections of plant tissues color 

 dull light blue (Emig, p. 58). 



Aceto-Carmine (Schneider's). Add 10 gms. 

 carmine to 100 cc. 45% aq. glacial acetic 

 acid. Dissolve with heat and bring up 

 to boiling. Cool, filter, and store as 

 stock solution. 



Acid Alcohol is used for the differentiation, 



or decolorization, of certain stains. 

 It is usually made by adding 1 cc. 

 hydrochloric acid to 99 cc. 70% ethyl 

 alcohol. It is also employed for clean- 

 ing cover glasses. 



Acid Alizarin Blue (1) G.R. (CI, 1048). An 

 acid anthraquinone dye called for in 

 Buzaglo's Method which the author pro- 

 poses as substitute for Van Gieson. 



(2) B.B. (CI, 1063) likewise an acid 

 anthraquinone dye little used, if at all. 



Acid Alizarin Green G (CI, 1049), a direct 

 mordant dye of color fastness 1. Use 

 for staining blue green and green algae 

 and paraffin sections of animal tissues 

 after mordanting in 1% aq. ferric alum 

 is described (Emig, p. 63). 



Acid Blue B (CI, 736), an acid dye of light 

 fastness 5 gives light, fugitive and in- 

 distinct coloration of tissue (Emig, 

 p. 52). 



Acid Blue G (CI, 712)— Brilliant Acid Blue 

 V — an acid dye of light fastness 5 (Emig, 

 p. 52). 



Acid Bordeaux, see Bordeaux Red. 



Acid Congo R, see Vital Red. 



Acid Dyes, see Staining. 



Acid Fast Bacilli. Of these the organisms 

 of tuberculosis and leprosy are the most 

 important. 



1. In smears apply Carbol Fuchsin 

 gently heat 3-5 min. or stain room 

 temperature 15 min.; decolorize 95% 

 ethyl alcohol containing 3% of cone, 

 hydrochloric acid until only slight pink 

 color remains; wash in water; counter- 

 stain sat. aq. methylene blue or Loef- 

 fler's Alkaline Methylene Blue; wash 

 and dry. 



2. In sections the organisms can be 

 stained red in parafiin sections after 

 almost any fixation (formalin-Zenker 

 preferred). First color with Harris 

 hematoxylin. Wash in water and per- 

 haps decolorize a little in Acid Alcohol. 

 Wash again. Stain with warmed carbol 

 fuchsin 1 hr. or more. Decolorize in 

 acid alcohol. Wash carefully in water 

 plus few drops ammonia. 95% ale, 

 abs. ale, xylol, balsam. A critique of 

 the methods has been published (Fite, 

 G. L., Am. J. Path., 1938, 14, 491-508). 

 To color the organisms blue, fix 3-5 days 

 or more in equal parts 10% formalde- 

 hyde and 95% alcohol. Stain sections 

 in new fuchsin 0.5 gm.; phenol crystals, 

 5.0 gm.; alcohol methyl or ethyl, 10 cc. 

 -f- aq. dest. to make 100 cc. at 60° C. 

 over night, 12-24 hrs. or at room tem- 

 perature 24-48 hrs. Longer for M. 

 leprae. Freshly distilled aq. formalde- 



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