DEHYDRATION 



79 



DIANIL BLUE 2R 



washing in 2 changes of chloroform. 

 Clearing is continued in chloroform for 

 imbedding in paraffin, or the tissue may 

 be passed from 95% alcohol, even from 

 80%, into Terpineol and cleared in half 

 terpineol and xylol. Still another way 

 to avoid absolute alcohol is to transfer 

 from 95% alcohol to Bergamot Oil 

 which serves as a clearing agent. 



Several substitutes for ethyl alcohol 

 as a dehydrating agent are available. 

 Acetone is the best known. Dioxan 

 will not only take the place of the alcohol 

 but also that of the clearing agent so 

 that it is possible to greatly simplify 

 the technique and make the sequence : 

 fixative to dioxan to paraffin. See 

 Dioxan and note as to possible danger 

 to those using it. Cellosolve has also 

 been proposed as a dehydrating agent. 

 Lee (p. 64) says that it is expensive, 

 inflammable and quickly takes up water 

 from the air. Whether it is injurious 

 when breathed remains to be deter- 

 mined. On the whole it appears that 

 little is to be gained by such substitutes. 

 However, Cyclohexanone deserves fur- 

 ther trial. If alcohol must be avoided 

 it is always possible to fix in formalin 

 and to use frozen sections. By the Alt- 

 mann-Gersh technique the tissues are 

 dehydrated in vacuo while still frozen. 



Dehydropyridines. Warburg noted a marked 

 whitish fluorescence in ultraviolet light. 

 Blaschko and Jacobson (Bourne, p. 196) 

 report that the pyridines do not show 

 this fluorescence and that the small gran- 

 ules that exhibit it in sections of living 

 liver tissue may well be dehydropyri- 

 dines. Their brilliant white fluores- 

 cence quickly fades. 



Delafield's Alum Hematoxylin. To 400 cc. 

 sat. aq. ammonia alum add 4 gms. 

 hematoxylin dissolved in 25 cc. 95% 

 ale. Leave exposed to air and light 4 

 days. Add 100 cc. methyl ale. and 10 

 cc. glycerin; filter. Filtrate will slowly 

 ripen. To hasten ripening add 10 cc. 

 hydrogen peroxide. 



Delta Dye Indicator, see Nitrazine. 



Dental Enamel, see Enamel. 



Dentin. Can be studied in ground sections 

 of undecalcified teeth as well as in 

 paraffin and celloidin sections of de- 

 calcified ones (see Teeth). For the 

 latter Hematoxylin and Eosin, Mal- 

 lory's Connective Tissue stain and 

 many others can be applied as in the 

 case of decalcified bone. Hanazawa's 

 (Dent. Cosmos, 1917, 59, 125) methods 

 for the minute structure of dentin are 

 given in detail by Wellings, A. W., 

 Practical Microscopy of the Teeth and 

 Associated Parts, London: John Bale, 

 Sons & Curnow. Ltd., 1938, 281 pp. 

 Dentin can be advantageously ex- 

 amined after vital staining with Alizarin 



Red S. Its pH can be estimated 

 (Grossman, L. I., J. Dent. Res., 1940, 

 19, 171-172). For determination of 

 rate of mineral replacement see Radio- 

 active Phosphorus; for Korff's fibers, 

 see Teeth, Developing; and for nerve 

 endings, see Teeth, Innervation. 



Desoxyribonucleic Acid. Method for deter- 

 mination in isolated nuclei of tumor 

 cells (Dounce, A. L., J. Biol. Chem., 

 1943, 151, 235-240). 



Destin's fixative. 1% aq. chromic acid, 99 

 cc; formalin, 6 cc; glacial acetic acid, 

 2 cc. After standing for a few days it 

 becomes green when it can be used. 



Detergents, see discussion of cutaneous 

 detergents by Lane, C. G. and Blank, 

 I. H., J.A.M.A., 1942, 118, 807-817. 

 See Aerosol. 



Deuterium is heavy hydrogen. It is an iso- 

 tope having atomic weight of 2.0135 and 

 the symbol IP. Schoenhoimer, R., 

 Harvey Lectures, 1937, 32, 122-144 em- 

 ployed deuterium combined with oxy- 

 gen as heavy water H^O to mark fatty 

 acids. In his experiments on mice, 

 held on a carbohydrate diet plus heavy 

 water the fatty acids of the body are 

 replaced by new fatty acids containing 

 deuterium. The rate of replacement of 

 fatty acids can therefore be deter- 

 mined. For further experiments along 

 this line see Symposium on Interme- 

 diate Metabolism of Fats. Biological 

 Sjanposia Lancaster: Jaques Cattell 

 Press, 1941. Leading references on 

 deuterium: Cope, O., Blatt, H. and 

 Ball, M. R., J. Clin. Invest., 1943, 22, 

 111-115; Flexner, L. B., Gellhorn, A. 

 and Merrell, M., ,J. Biol. Chem., 1942, 

 144, 35-40; Stern, K. and Dancey, T. E., 

 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. 



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. 



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. IL, Am. J. Physiol., 1918, 

 46, 483-186 and Sutter, M., Anat. Rec, 

 1916, 16, 164-165 for dye employed by 

 them in study respectively of corpora 



