DEUTROPLASM 



99 



CENTRIFUGATION OF 

 PARTICULATES 



Proc. Soc. Exp. Biol. & Med., 1941, 48, 

 619-620. 



Deutoplasm, see Paraplasm. 



Diacetin (glycerol diacetate) use in flatten- 

 ing paraffin sections (Carleton, H. M. 

 and Leach, E. H., J. Path. & Bact., 



1939, 49, 572-576). 



Diamin Red 4B, see Benzopurpurin 4B. 



Diamine Bordeaux CGN, see Erie Garnet B. 



Diaminoacridines have marked affinity for 

 nuclei in vivo. They can be visualized 

 by their fluorescence in near ultraviolet 

 light. Their localization resembles the 

 chromatin pattern as revealed by "nu- 

 clear" dyes. These compound are ap- 

 parently not toxic because regeneration 

 of rat liver cells while they are still 

 within the nuclei takes place at the 

 same rate as in controls (DeBruyn, R. 

 S., Anat. Rec, 1950, 108, 279-307). 



Di-Amino Tri-Phenyl Methane Dyes. Ex- 

 amples : brilliant green, fast green FCF, 

 light green SF yellowish and malachite 

 green. 



Diamond Green, see Brilliant Green. 



Diamond Green B, BX or P Extra, see 

 Malachite Green. 



Diamond Fuchsin, see Basic Fuchsin. 



Dianil Blue H3G, see Trypan Blue. 



Dianil Blue 2R (CI, 265)— benzo new blue 

 2B, direct steel blue BB, naphthamine 

 brilliant blue 2R — Conn (p. 63) gives 

 the same formula for this acid dis-azo 

 dye as that supplied by Corner, G. W. 

 and Hurni, F. H., Am. J. Physiol., 1918, 

 46, 483-486 and Sutter, M., Anat. Rec, 

 1916, 16, 164-165 for dye employed by 

 them in study respectively of corpora 

 lutea and mammary glands but these 

 authors do not employ the name : dianil 

 blue. 



Dianil Red 4B, see Benzopurpurin 4B. 



Dianthine B, see Erythrosin, bluish. 



Diaphane for mounting Giemsa preparations 

 (Coulston, F., J. Lab. & Clin. Med., 



1940, 26, 869-873). 



Diaphanol is according to Lee (p. 598) the 

 trade name for a mixture, formerly 

 obtainable from Leitz, produced by 

 passing chlorine dioxide vapor into ice 

 cold 70% acetic acid. It should be 

 fresh. He advises against attempts to 

 make it and outlines its use in the soft- 

 ening of Chitin. Rinse well fixed tissues 

 in 63% alcohol and transfer them to 

 diaphanol until they are softened and 

 bleached. If the diaphanol becomes 

 discolored, repeat. Transfer to 63% 

 alcohol, dehydrate, clear in tetralin 

 (if not available, benzol) and imbed in 

 paraffin. See use of diaphanol in 

 demonstrating Melanins. 



Diazin Black, see Janus Black. 



Diazin Green, see Janus Green B. 



Diazo Reaction. Serra, J. A., Stain Techn., 

 1946, 21, 5-18 gives the technique as 



follows : Prepare tissue as described 

 under Ninhydrin Reaction. "Treat the 

 pieces for 2-3 minutes with a saturated 

 aqueous solution of sodium carbonate; 

 afterwards add some drops of the diazo 

 reagent and stir the liquid well. Ob- 

 serve in glycerin. (The coloration de- 

 velops rapidly and lasts for some days.) 

 Preparation of the diazo-reagent: into 

 a 50 ml. flask immersed in an ice bath, 

 pour 1.5 ml. of a sulphanilic acid solu- 

 tion (dissolve 0.9 g. of pure sulphanilic 

 acid in 9 ml. of concentrated HCl and 

 add water to 100 ml.); add 1.5 ml. of a 

 5% aqueous solution of NaN02, shaking 

 the flask meanwhile. After 5 minutes 

 in the ice bath add, also while shaking, 

 another 6 ml. of nitrite. After 5 min- 

 utes fill up to 50 ml. with cooled dis- 

 tilled water. The reagent must be 

 prepared every day and kept in the ice 

 chest. 



"The reaction gives an orange or yel- 

 low color with the histidine and the 

 tyrosine of the proteins." 



Dichlorofluorescein. Structure of, Milligan, 

 R. F. and Hope, F. J., J. Am. Chem. 

 Soc, 1945, 67, 1507-1508. 



Dientamoeba fragilis. Technique of stain- 

 ing and points to be considered in diag- 

 nosis (Hood, M., J. Lab. & Clin. Med., 

 1939-40, 25, 914-918). 



Diethylene Dioxide = Dioxan. 



Diflferential Centrifugation of Cell Particu- 

 lates — Written by Joseph A. Falzone, 

 Department of Anatomy, Washington 

 University Medical School, St. Louis. 

 November 27, 1951 — Since the pioneer- 

 ing work of R. R. Bensley and N. Hoerr 

 (Anat. Rec, 1934, 60, 449-455), this 

 technique has proven one of the most 

 versatile and direct in the armamen- 

 tarium of cytology. In essence it con- 

 sists of a rather drastic mechanical 

 disruption of large numbers of cells in 

 various media, separation of the result 

 ing particulates by centrifugation, and 

 determination of chemical components 

 and enzymatic activities in these frac- 

 tions. There are almost as many varia- 

 tions in the technique as investigators, 

 each variation having its peculiar merits 

 or limitations, the one chosen depend- 

 ing upon the particular cell organ- 

 elle or chemical data desired. 



The obvious and inherent weakness 

 of these methods is their tendency to 

 produce morphological and chemical 

 artefacts. For example, when a tissue 

 is homogenized in an aqueous medium, 

 enzymes and other substances may be 

 lost by denaturation or solution, or 

 what is worse, adsorbed to particulates 

 that never contained them in life. 

 Large particles may fragment and sedi- 

 ment with an unrelated small granule 



