DILATOMETRIC TECHNIQUES 



102 



DIRECT GARNET R 



cholesterol. This has been adapted to 

 histochemical use by Brunswick and 

 by Leulier and Noel (A., and R., Bull. 

 d'Hist. Appl., 1926, 3, 316-319). Lison 

 (p. 211) recommends a slight change. 

 Immerse frozen sections of formalin 

 fixed tissue in 0.5% digitonine in 50% 

 ale. for several hrs. Rinse in 50% ale, 

 then in water and mount in Apathy's 

 syrup or glycerin gelatin. With 



crossed nicols (polarizing microscope) 

 one observes appearance of needles or 

 rosettes of the complex cholesterol- 

 digitonide. To resolve this complex 

 stain with sudan. The esters will color 

 and lose their birefringence while the 

 cholesterol will remain uncolored and 

 retain birefringence. 



Dilatometric Techniques. These have been 

 adjusted so that they will give the fine 

 quantitative measurements needed in 

 histochemistry by Linderstr0m-Lang, K 

 Nature, 1937, 139, 713. He reported 

 especially ultra-microestimations of 

 peptidase activity. 



Di-Nitrosoresorcinol test for iron, see Iron. 



Diodrast, trade name for an organic iodine 

 preparation recommended by Gross, S. 

 W. (Proc. Soc. Exp. Biol. & Med., 

 1939, 42, 258-259) for injection into com- 

 mon carotid with later x-ray photo- 

 graphs of the vascular tree. For visual- 

 ization of ventricular chambers and 

 large arteries see method of Ponsdome- 

 nech, E. R. and Nunez, V. B., Am. 

 Heart J. 1951, 41, 643-651. 



Dioxan is diethylene dioxide. It mixes 

 with water, ethyl alcohol, many clearing 

 agents and paraffin (slightly). McClung 

 (p. 39) recommends its use to replace 

 ordinary agents like xylol. Dioxan 

 fumes are said to be dangerous to 

 laboratory workers so that it should be 

 used under a hood or in a well ventilated 

 room with container covered when not 

 in use (Magruder, S. R., J. Lab. & Clin. 

 Med., 1937-38, 23, 405-411). 



For fixation the following mixtures 

 are recommended (McClung, p. 39) : 

 (1) Sat. aq. picric acid, 5 parts; glacial 

 acetic, 1 part; dioxan, 4 parts. (2) 

 Sat. picric acid in dioxan , 4 parts ; glacial 

 acetic, 1 part; absolute alcohol, 4 parts. 

 Graupner and Weissberger (von H. and 

 A., Zool. Anz., 1933, 102," 39-44) suggest: 

 dioxan 80%, methyl alcohol 20%, paral- 

 dehyde 2%, and acetic acid 5%. See 

 Clearing, Pituitary. See as ingredient 

 of Lison's gh'cogen method; also dioxan 

 imbedding of Pituitary. 



A method for the dehydration, puri- 

 fication and clarification of dioxan so 

 that its use in tissue technique can be 

 continued has been described by Hall, 

 W. E. B., Am. J. Clin. Path., 1943, 7 

 (Technical Section), 98-100. 



Dipeptidase can be localized in chief cells 

 of stomach. See review of methods 

 (Gersh, I., Physiol. Rev., 1941, 21, 

 242-266). 



Di-Phenyl Methane Dyes. Of these only 

 auramin need be referred to. 



Diphosphopyridine Nucleotide, see tech- 

 nique of Anfinsen, C. B., J. Biol. Chem., 

 1944, 152, 285-291. 



Diphtheria Bacilli. 1. Neisser's stain 



(Stitt, p. 863). A = methylene blue, 

 0.1 gm.; 95% ale, 2 cc; glacial acetic 

 acid, 5 cc; aq. dest., 95 cc. B = 

 Bismark brown, 0.2 gm. ; aq. dest. (boil- 

 ing) 100 cc. Dissolve and filter. To 

 stain smear pour on A , 30-60 sec. Wash. 

 Then B, 30 sec. Wash in water, dry 

 and mount. Bacilli brown with dark 

 blue dots at either end. Better results 

 can be secured by adding 1 part of 

 crystal violet (Hoechst) 1 gm.; 95% 

 ale, 10 cc; aq. dest., 300 cc. to 2 parts 

 of A before using. Chrysoidin 1 gm. 

 in hot aq. dest. 300 cc. is more satis- 

 factory counterstain than Bismark 

 brown. Most American brands of crys- 

 tal violet are satisfactory. 



2. Pander's stain (Stitt, p. 863). 

 Toluidin blue (Grubler) 0.02 gm.; aq. 

 dest., 100 cc; glacial acetic acid, 1 cc ; 

 abs. ale, 2 cc Add small amount to 

 fixed film on cover glass. Invert and 

 mount on slide. Diphtheria bacilli 

 recognizable by metachromatic granules 

 intensely stained, diphtheroids by their 

 strong color in contrast with ordinary 

 cocci and bacilli the bodies of which 

 are only faintly blue. 



3. Laybourn's modification of Albert's 

 stain (Stitt, p. 863). A = toluidin 

 blue, 0.15 gm. ; malachite green, 0.2 gm. ; 

 glacial acetic acid, 1 cc. ; 95% ale, 2 

 cc, aq. dest., 100 cc. B = iodine 

 crystals, 2 gm.; potassium iodide, 3 

 gm.; aq. dest., 300 cc. Let both stand 

 24 hrs. and use filtrate. Apply A to 

 heat fixed smears 3-5 min. Wash in 

 water. Apply B for 1 min. Wash, 

 blot and dry. Granules of diphtheria 

 bacilli, black; bars, dark green; inter- 

 mediate parts, light green and all three 

 in sharp contrast. 



Diplosome, a double centrosome. 



Direct Black, see Chlorazol Black E. 



Direct Fast Orange (CI, 326)~Erie Fast 

 Orange (NAC), Erie Fast Scarlet YA 

 (NAC) — a direct disazo dye of light 

 fastness 3 (Emig, p. 38). 



Direct Fast Scarlet 4 BS (CI, 327)— Pont- 

 amine Fast Scarlet 4 BS of DuPont — , a 

 disazo direct dye of light fastness 3, can 

 be employed instead of carmine as a 

 general stain. Details of use in study 

 of plant and animal tissues are de- 

 scribed (Emig, p. 38}. 



Direct Garnet R, see Erie Garnet B. 



