FUCHSIN NB 



133 



FUNGI 



ance of living tissues — is obtained by 

 dehydrating at temperatures below 

 — 3(J°C. If the freezing can be effected 

 rapidly enough, the constituents of a 

 tissue are not appreciably changed 

 morphologically. 



Die Elementarorganismen und ihre 

 Beziehungen zu den Zellen, Altmann, 

 R., /Leipzig, Veit and Co., 1890, intro- 

 duced the method of freezing tissues 

 and dehydrating them over sulfuric 

 acid in vacuo at temperatures below 

 -15°C. Gersh, I. (Anat. Rec, 1932, 

 53, 309-337) overcame many early diffi- 

 culties and elaborated the technic so 

 that good histologic fixation could be 

 procured on a number of tissues. 

 Packer, D. M. and Scott, G. H. (J. 

 Tech. Methods, 1942, 22, 85-96) have 

 overcome, by a newly designed cryo- 

 stat, many of the dehydration difficul- 

 ties. The frozen dehydration method 

 has been of value in the preliminary 

 fixation of tissues for a study with the 

 electron microscope of the localization 

 of their contained salts by microincin- 

 eration. It has been used for the pre- 

 liminary preparation of tissues in the 

 study of mitochondria and Nissl sub- 

 stance, of secretion in the stomach and 

 the thyroid gland, and in a histochemi- 

 cal study of the Golgi apparatus. More 

 extended discussions of the process of 

 freezing and of the subsequent process 

 of dehydration, with considerations of 

 the advantages and limitations of the 

 method are given by Hoerr, N. L. 

 (Anat. Rec, 1936, 65, 293-295) and 

 Simpson, W. L. (Anat. Rec. 1941, 80, 

 173-189). 



A number of cryostats have been 

 designed recently, including those by 

 Stowell, R. E. (Stain Technology, 1951, 

 26, 105-108) Emmel, V. M. (Anat. Rec, 

 1946, 95, 159-175) Scott, G. H., and 

 Hoerr, N. L. (Medical Physics, 1950, 

 2, 292-296) Wang, K. J., and Grossman, 

 M. I. (J. Lab. and Clin. Med., 1949, 

 34, 292-296) and Mendelow, H., and 

 Hamilton, J. B. (Anat. Rec, 1950, 107, 

 443-451). A good commercial design 

 is available from Scientific Specialties 

 Corporation, Cambridge, Mass., or 

 Euclid Glass Engineering Laboratory, 

 11310 Wade Park Avenue, Clevelend, 

 Ohio. 



Fuchsin NB, see New Fuchsin. 



Fuchsin S, SN, SS, ST or S III, see Acid 

 Fuchsin. 



Fungi. — Written by Morris Moore, Barnard 

 Free Skin and Cancer Hospital, St. 

 Louis, Mo. November 10, 1951. 



1. Skin scrapings and hair. The 

 usual method is to mount the material 

 in an alkali — either sodium hydroxide 

 (NaOH) or potassium hydroxide 



(KOH). The latter is preferable and 

 should be used in a 10-30% solution. 

 For rapid work 40% is employed but this 

 tends to swell and disintegrate the 

 fungi. A weak solution takes longer to 

 clear the skin. The skin usually clears 

 in 5 min. to 2 hrs. in concentrations of 

 10-30%. A little heat helps. Use sub- 

 dued light in order to avoid high lights. 

 The fungus is clearly discernible against 

 the irregular nondescript background 

 of skin which is usually clear. Dip 

 infected hairs taken from scalps, par- 

 ticularly those that are oily, in ether or 

 in alcohol (absolute alcohol is preferable 

 to 95%) for a moment in order to get rid 

 of the oil which often simulates spores 

 in sliape and size. 



Adamson (H. G., Brit. J. Dermat., 

 1895, 7, 201-211, 237-244) has recom- 

 mended clearing with 5-10% KOH and 

 staining by the Gram method. Chal- 

 mers and Marshall (A. J. and A., J. Trop. 

 Med. Hyg., 1914, 17, 256-265, 289-291) 

 suggest soaking scales in 40% KOH for 

 some hours in a watch glass in an in- 

 cubator at 40 °C. Transfer specimens 

 to watch glass containing 15% alcohol for 

 30 min., remove to slide, allow alcohol 

 to evaporate and dry over flame ; stain 

 with Anilin-Gentian Violet for 20 min. 

 Treat with Gram's Iodine for 3 min.; 

 decolorize with anilin oil, 30 min.; stain 

 in concentrated alcoholic eosin, 1 min.; 

 wash off eosin with anilin oil or clove oil ; 

 treat with xylol and mount in balsam. 



Priestley (H., Med. J. Australia, 

 1917, 2, 471-475) recommends lacto- 

 phenol (lactic acid, 1 part; phenol, 1 

 part; glycerol, 2 parts, aq. dest., 1 part) 

 for clearing instead of 40% KOH ; or 

 chloral hydrate crystals, 2 parts; lactic 

 acid, 1 part; phenol crystals, 1 part, 

 may be used. For thick material 

 Langeron suggests : chloral hydrate 

 crystals, 40 gm. ; phenol crystals, 40 

 gm.; lactic acid (U.S.P.), 20 gm.; and 

 sodium salicylate, 10 gm. Slight heat 

 facilitates clearing. To stain, Priestley 

 recommends treatment with chloroform 

 to remove the fat; boiling, 2-3 min., 

 with formic acid ; washing for a few 

 minutes in water and staining with 

 Sahli's methylene blue : after which the 

 tissue is to be washed, differentiated 

 with alcohol if necessary, dehydrated, 

 cleared and mounted in balsam. 



Bachman (R. W., Arch. Dermat. & 

 Syph., 1920, 1, 50-54) recommends the 

 following procedure : Place scrapings in 

 a drop of water on a cover slip, tease 

 thoroughly with a dissecting needle, 

 dry over a flame but do not scorch. 

 Stain for 2 min.; decolorize in 95% al- 

 cohol, 15-30 sec; immerse in aq. dest., 

 15-30 sec. ; pour off excess, dry by heat, 



