GROWTH 



116 



HEAVY WATER 



can be revealed by mitotic counts 

 (Mitosis). The amount of bone or of 

 dentine laid down while Alizarin S 

 or Madder is in the circulation can be 

 estimated. The amount of radioactive 

 isotropes accumulated is a third method 

 (see Radioactive Phospliorus) if the 

 amount increases per unit of time while 

 elimination of the nonradioactive ele- 

 ment in question remains the same. 

 Valuable histochemical methods are 

 given by Lowry, O. H. and Hastings, 

 A. B., in Cowdry's Problems of Ageing, 

 Baltimore : Williams and Wilkins, 1942, 

 936 pp. 



Guanin appears as white granules in retinal 

 tapetum of certain animals including 

 nocturnal ones. Decreases in amount 

 in regions containing more fuscin. 

 For details see Arey, L. B. in Cowdry's 

 Special Cytology, 1932, 3, 1218. 



Guarnieri Bodies, cytoplasmic inclusions in 

 smallpox and vaccinia. See Inclusion 

 Bodies and Cowdry, E. V., J. Exper. 

 Med., 1922, 36, 667-684 for supravital 

 staining with brilliant cresyl blue. For 

 sections Giemsa's stain is excellent. 



Gum Damar, see Daniar. 



Hafnium, see Atomic Weights. 



Hairs.— Written by Mildred Trotter, Dept. 

 of Anatomy, Washington University, 

 St. Louis, May 15, 1946.— The hair shaft 

 (above the surface of the skin), the hair 

 root (below it) and the hair follicle 

 (encasing the root) call for somewhat 

 different techniques. 



The shaft may be examined in a dry 

 mount after first washing thoroughly 

 and repeatedly in ether-alcohol, or the 

 shaft and root can be cleared and 

 mounted in balsam for repeated study. 

 In case it is too highly pigmented to 

 permit a clear view of its structure first 

 bleach with hydrogen peroxide. In- 

 dividual cells of the shaft can be iso- 

 lated by maceration in 40% aq. po- 

 tassium hydrate. 



Determination of the cuticular scale 

 pattern may be made after partially 

 embedding the hair in a glycerine jelly 

 (Eddy, M. W. and Raring, J. C, Proc. 

 Acad. Sci., 1941, 15, 164-168). Study 

 of the cortex (fusi and pigment granules 

 under very high power) and medulla 

 (when present with its clumps of pig- 

 ment) requires clearing by immersing 

 in some oil the refractive index of which 

 is approximately the same as that of the 

 hair (Hausmann, L. A., Sci. Month., 

 1944, 59, 195-202). 



Cross sections of a large number of 

 hairs (approximately 150) may be made 

 at one time with very little preliminary 

 preparations by using the "Dr. J. I. 

 Hardy Thin Cross-Section Device", 

 (Gosnell Mfg. Co., Washington, D. C). 



The root and the follicle are to be 

 seen in most sections of hairy skin and 

 require no special technique unless one 

 wishes to study the follicles attached to 

 whole mounts of epidermis or to mark 

 them in order to follow their cyclic 

 changes. Distribution of alkaline 

 phosphatase in growth of hair follicle 

 (Johnson, P. L., Butcher, E. O. and 

 Bevelander, G., Anat. Rec, 1945, 93, 

 355-361). For further details see Trot- 

 ter, M., chapter on Hair in Cowdiy's 

 Special Cytology, 1932, 1, 40-65. 

 Cleaning and mounting of individual 

 hairs (Duncan, F. W., J. Roy. Micr. 

 Soc, 1943, 63, 85-88. Microphotog- 

 raphy of keratin fibers of hairs (Stoves, 

 J. L., J. Roy. Micr. Soc, 1943, 63, 89- 

 90). The less pigment in the hair, the 

 greater the fluorescence, so that gray 

 hair is clear white. Hair containing 

 tricophyton or microsporon fluoresces 

 bright green. See Kinnear, J., Brit. 

 Med. J., 1931, 1, 791-793 on diagnosis of 

 ringworm. 



Halides, microscopic localization in tissues 

 by precipitation methods (Gersh, I. 

 and Stieglitz, E. J., Anat. Rec, 1933, 

 56, 185). 



Hanging Drop preparations are mostly em- 

 ployed in the examination of living 

 bacteria and protozoa. A drop of the 

 fluid is simply attached to the under 

 surface of a cover glass which is mounted 

 over a depression in a slide. Equally 

 satisfactory results can usually be 

 obtained by simply mounting under a 

 cover glass on an ordinary slide unless 

 the greater depth of the hanging drop is 

 required. When in Microdissection it 

 is necessary to get at the cells from the 

 under surface of the cover glass special 

 chambers and hanging drops are em- 

 ployed. 



Harderian Glands, fluorescence in mice 

 (Strong, L. C. and Figge, F. H. J., 

 Science, 1941, 93, 331). Technique for 

 rat is given by Grafflin, A. L., Am. J. 

 Anat., 1942, 71, 43-64. 



Harris Alum Hematoxylin. Dissolve 1 gm. 

 hematoxylin in 10 cc absolute alcohol 

 and 20 gms. ammonium or potassium 

 alum in 200 cc. aq. dest. the latter with 

 the aid of heat. Mix the 2 solutions, 

 bring quickly to boiling and add 0.5 gm. 

 mercuric oxide. Solution turns purple. 

 Cool quickly in cold water bath. Mal- 

 lory (p. 72) recommends adding 5% of 

 acetic acid. 



Heart, see Coronary Arteries, Myocardium, 

 Pericardium, Purkinje Cells and Fibers. 



Heavy Water is water in which deuterium, 

 the heavy hydrogen isotope H^, has 

 taken the place of ordinary hydrogen. 

 See Deuterium which is used as a tracer 

 substance. 



