TECHNIQUES 



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

 Special Cytology, 1932, 2, 1173-1210. 



Abopon. For mounting amyloid stains 

 (Leib, Am. J. Clin. Path., 1947, 17, 413). 



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). See X-ray Ab- 

 sorption. 



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). See V. Apathy's Syrup. 



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). 



Acetic-Carbol— Sudan III, see Sudan III. 



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. Used for smears this 

 combines fixation with staining; but 

 it causes a swelling of some cellular 

 elements and is not recommended. 



Aceto-Orcein-Fast-Green. — Written by Dr. 

 N. B. Kurnick, Dept. of Medicine, 

 Tulane University, New Orleans 12. 

 January 31, 1951 — This modification of 

 La Cour's aceto-orcein stain-fixative 

 for chromosomes permits a one-step 

 difi"erential staining of tissues. The 

 introduction of fast green and NaCl 

 (to prevent overstaining by the former) 

 provides a green counterstain for the 

 reddish-brown chromatin. The intensity 

 of this counterstain may be modified by 

 varying the salt concentration (increas- 

 ing the salt concentration reduces the 

 intensity of green staining), but the 

 method described here has proved satis- 

 factory for most materials. The stain 

 mixture may be used as a stain-fixative, 

 as for dipteran salivaries, some plant 

 materials, and for the study of isolated 

 chromosomes and nuclei, or as a stain 

 following other fixatives. Flood ma- 

 terial for few minutes in following solu- 

 tion: 27 ml. 1% orcein in 45% acetic 

 acid, 3 ml. 1% fast green in 95% alcohol, 

 2 ml. 2M NaCl; cover with cover slip, 

 press out on filter paper, if desired. 

 Paraffin sections must be brought to 

 water before staining Permanent 

 mounts may be prepared by rinsing 

 the stained material successively in 

 70%, 95%, 100% alcohol, xylene, and 

 mounting in Clarite. Cytoplasm, col- 

 lagen, and nucleoli are green, chromatin 

 is reddish-brown (Kurnick, N. B., C^old 

 Spring Harbor Symp. Quant. Biol., 

 1947, 12, 191; Kurnick, N. B. and Ris, 

 Hans, Stain Tech., 1948, 23, 17-18). 



Acetone, see Dehydration of Tissues, as 

 fixative for Phosphatases and Lipases. 



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. 



