WEIL'S METHOD 



267 



WO.AJD 



iron alum until gray matter or degener- 

 ated areas become recognizable. Wash 

 3 times in tap water. Differentiate 

 over white background to desired de- 

 gree in: borax, 2.5 gm.; potassium forri- 

 cyanide, 12.5 gm.; aq. dest., 1000 cc. 

 (For paraffin sections, differentiate just 

 long enough in 4% aq. iron alum to 

 remove stain from back of slide. Care 

 should be taken not to over-differen- 

 tiate, for in so doing fine fibers are lost). 

 Wash 2 times in tap water and next in 

 aq. dest., to which 28% ammonia had 

 been added (6 drops to 100 cc. of water) . 

 Dehydrate in 95% ale, abs. ale. and 

 ether (equal parts), clear in .xylol and 

 mount in balsam or claritex. Revised 

 bv A. Weil, Northwestern University 

 Medical School, Chicago, 111. May 14, 

 1946. 



Weld, a plant. Reseda luteola which yields a 

 yellow dye. The use of this source of 

 yellow coloring matter is said to be of 

 greater antiquity than any other source 

 of yellow dye. It was employed to dye 

 the clothes of the six vestal virgins 

 whose responsibilitj^ it was to keep the 

 fire burning in the temple of Vesta in 

 Rome (Leggett, W. F., Ancient and 

 Medieval Dyes. Brooklyn: Chemical 

 Publishing Co., Inc. 1944, 95 pp.). 



Wetting Agents. These have been used in 

 experiments designed to increase the 

 rapidity of penetration of fixatives by 

 Chermock, R. L. and Muller, H. E. 

 Science, 1946, 103, 731-732. They found 

 that Tergitol-4 when added to 10% for- 

 malin, Zenker's fluid and some others 

 improved fixation and staining. Tergi- 

 tol-08 was also an advantage when 

 employed in Zenker's fluid. The 

 authors give the literature on the 

 subject. 



Wetting Properties. An interesting method 

 for investigating the cell membrane is 

 to measure its wetting properties. The 

 Mudds (S., and E. B. H., J. Exp.Med., 

 1926, 43, 127-142; J. Gen. Physiol., 1931, 

 14, 733-751) have noticed the responses 

 of cells to a film of oil advancing between 

 slide and cover glass. Erythrocytes 

 are easily wetted by the oil; whereas, 

 when leucocytes are surrounded by the 

 film of oil, the oil does not wet their sur- 

 faces but remains separated from them 

 by thin films of saline solution. The 

 Mudd's thought that this indicated that 

 the surface of erythrocytes is lipoid and 

 that of leucocytes protein. Danielli 

 (Bourne, p. 78) has expressed the view 

 tliat the surfaces of both cells are prob- 

 ably coated with protein, the erythro- 

 cytes with serum albumen and the leu- 

 cocytes with serum globulin. The wet- 

 ting technique lias been employed in a 

 considerable number of experiments. 



Dawson and Belkin, J. A. and M., Biol. 

 Bull., 1929, 56, 80-86 and Marsland, D., 

 J. Cell. & Comp. Physiol., 1933, 4, 9-33 

 worked with amebae and Clmmberd,R., 

 Biol. Bull., 1935, 69, 331, and Kopac, M. 

 J. and Chambers, R., J. Cell. & Comp. 

 Physiol., 1937, 9, 331-361 with naked 

 arbacia eggs. Sec Cell Membranes. 



Whole Mounts of tissues which are fairly 

 thick are often very useful. See Elood 

 Vessels, Cartilaginous Skeleton, Cor- 

 rosion Preparations, Epidermis, In- 

 sects, Mammary Glands, Nerve End- 

 ings, Ossification, etc. 



Wilder's Method of silver impregnation for 

 reticular fibers (Wilder, H. C, Am. J. 

 Path., 1935, 11, 817-819). Fix in 10% 

 formalin, Zenker or formalin-Zenker. 

 Treat paraffin, celloidin or frozen section 

 in 0.25% aq. potassium permanganate or 

 in 10% aq. phosphomolybdic acid for 1 

 min. Rinse in aq. dest. and transfer to 

 hydrobromic acid (Merck's cone. 34%, 

 1 part; aq. dest., 3 parts) for 1 min. 

 This can be omitted after phosphomolyb- 

 dic acid. Wash in tap water and in aq. 

 dest., then dip in 1% aq. uranium nitrate 

 (sodium free) 5 sec. or less. Wash in 

 aq. dest. 10-20 sec. and place in Foot's 

 silver diamino hydroxide for 1 min. To 

 make this: add S.1% aq. NH4OH drop by 

 drop to 5 cc. 10.2% aq. AgNOs until 

 brown ppt. is just dissolved. Then add 

 5 cc. 3.1% aq. NaOH and sufficient 

 NH4OH to just dissolve ppt. Make up 

 to 50 cc. with aq. dest. Dip quickly in 

 95% ale. and reduce for 1 min. in : aq. 

 dest., 50 cc; 40% neutral formalin 

 (neutralized with magnesium carbon- 

 ate), 0.5 cc; 1% aq. uranium nitrate, 

 1.5 cc. Wash in aq. dest. Tone in 

 1:500 gold chloride (Merck's reagent), 

 1 min. Rinse in aq. dest. and treat with 

 5% aq. sodium thiosulphate (hyposul- 

 phite), 1-2 min. Wash in tap water. 

 Counterstain as desired, dehydrate, 

 clear and mount in balsam. Reticular 

 fibers black. Note author's figures of 

 lymph nodes. 



Wilson's stain for Leishmania is compli- 

 cated. Details are provided by Craig, 

 p. 147 in whose opinion it gives no better 

 results than Wright or Leishman stains. 



Windaus, see Digitonine Reaction. 



Wintergreen Oil (methyl salicylate) is used 

 in the Spalteholz Method of clearing. 



Woad is a blue dye derived from the plant 

 Isatis tinctoria, now only of historic 

 interest, as it was replaced by indigo 

 after over a 1,000 years of supremacy in 

 Europe. When, nearly 2,000 years ago, 

 Julius Caesar's Roman legions crossed 

 the English Channel they encountered 

 a race of Celtic origin which they called 

 "Picts", or painted people, because 

 they had punctured their skins with 



