NECROSIS 



16S 



NEOPRENE 



crease in temperature, confers renewed 

 vitality (see Luyet, B., C. rend. Soc. 

 de bioL, 193S, 127, 788-789 and many 

 others). Death can therefore be better 

 defined as the disorganization of living 

 matter which makes permanently im- 

 possible all vital phenomena. Since 

 the organization of different sorts of 

 living cells is fundamentally different 

 the loss of organization in them is likely 

 also to be different. See various forms 

 of Degeneration. In general necrosis 

 of tissue is often evidenced by a break- 

 ing up of the nucleus known as caryor- 

 rhexis (G. Karyon, nucleus, + rhexis, 

 rupture) or by its solution, caryolysis 

 (G. lysis, solution). Consequently any 

 good nuclear strain such as hematoxylin 

 or methylene blue is satisfactory. See 

 techniques for Dead Cells, Necrobiosis. 

 Negative Stains are used to show the back- 

 ground in which bacteria and other 

 organisms are present in smears and by 

 contrast thus to reveal them unstained, 

 that is in a negative way. The tech- 

 nique is very simple. Simply mix the 

 fluid containing the organisms with the 

 "stain", smear en a slide, dry and 

 examine. Higgins' India Ink is usually 

 employed; but congo red (Cumley, 

 R. W., Stain Techn., 1935, 10, 53-50) 

 and azo blue (Butt, E. M., Boynge, 

 C. W. and Joyce, R. L., J. Inf. Dis., 



1936, 58, 5-9) are among many other 

 materials used. See Azo Blue. 



Negri Bodies. 1. Rapid section method 

 (Schleifstein, J., Am. J. Pub. Health, 



1937, 27, 1283-1285). Fix in Zenker's 

 fluid, wash, dehydrate in dioxan, embed 

 in paraffin, cut at 4 microns, mount, 

 deparaffinize. Flood slides with 1 drop 

 1 :40,000 aq. KOH in 2 cc. stock solution 

 of stain (Rosanilin of Grubler 1.8 gm., 

 methylene blue, Nat. Col., 1 gm., gly- 

 cerollOO cc. and methyl alcohol 100 cc). 

 Steam gently 5 min. Rinse in tap water. 

 Decolorize by gently moving in 90% 

 ethyl alcohol until color is faintly violet. 

 Pass quickly through 95% alcohol, 

 absolute, xylol and mount in_ balsam. 

 Negri bodies deep magenta with dark 

 blue inclusions. 



2. Rapid smear method (Dawson, 

 J. R., J. Lab. & Clin. Med., 1934-35, 

 20, 659-663). Remove brain to be 

 examined as quicklj'^ as possible, put 

 several small segments (3-4 mm. thick) 

 from Ammon's horn perpendicular to 

 its long axis and place in Petri dish. 

 Cut away adjacent tissue leaving only 

 the horn. Place a segment, cut surface 

 down, on small end of a new 1 in. cork. 

 With wooden applicator, or match, 

 gently wipe peripheral tissue outwara 

 and downward. The segment is thus 

 more firmly attached to the cork and 



the gray matter containing the pyra- 

 midal cells bulges upward. Press this 

 gently against a slide (clean and entirely 

 free from grease) held at one end be- 

 tween thumb and forefinger. Repeat 

 3 or 4 times, starting at end away from 

 fingers, quickly so tissue does not dry. 

 Immediately immerse in abs. methyl 

 alcohol 5 min. or more. Rinse in run- 

 ning water and stain in 2% aq. phloxine 

 2-5 min. Wash off excess stain in run- 

 ning water and color in Loeffier's alka- 

 line methylene blue, 10-20 sec. De- 

 colorize in 80% ethyl ale, dehydrate in 

 95% and 2 changes of absolute, clear in 

 xylol and mount in balsam. Handle 

 slides with forceps and avoid danger 

 from contact with tissue throughout 

 process. Pyramidal cells blue, Negri 

 bodies bright red to reddish brown. 

 Time including examination 25 min. 

 Stovall, W. D. and Black, C. E., 

 Am. J. Clin. Path., Tech. Suppl., 1940, 

 4, 8 recommend control of pH in staining 

 with eosin methylene blue (see Buffers) . 

 Stain with 1% eosin in 95% alcohol at 

 pH 6.0 or more alkaline. Negri bodies 

 pale red. The red is much more intense 

 if the pll is 3.0. Loeffler's methylene 

 blue is best as counterstain at pH 5.3. 

 At pH 6.0 it removes eosin. 



Azur B is advised for staining of Negri 

 bodies bv Jordan, J. H., and Heather, 

 H. H., S"tain Techn., 1929, 4, 121-126; 

 see also Carbol-Anilin Fuchsin methyl- 

 ene blue. 



Neisserian infection. A differential stain 

 favorable for diagnosis (Scudder, S. A., 

 StainTechn., 1931,6, 99-105). 



Neisser's Stain for Diphtheria Bacilli, 

 which see. 



Nemathelminthes is the phylum of round 

 worms. See Parasites. 



Nematodes. See Glychrogel for mounting. 

 See Parasites. 



Neodymium, see Atomic Weights. 



Neon, see Atomic Weights. 



Neoprene, injection of blood vessels (Lieb, 

 E., J. Tech. Methods, 1940, 20, 50-51). 

 Neoprene is a colloidal, finely divided 

 suspension of synthetic chloroprene in 

 an alkaline aqueous medium. Instruc- 

 tions for the human kidney. Cannulate 

 renal artery and wash with tap water 

 at slow but constant rate. Ligate grosslj'- 

 leaking vessels. Continue 8-18 hrs. 

 until organ is pale graj'. Cover and 

 keep in ice box 6-7 hrs. or until the 

 next day. Keep specimen at room 

 temperature about one hour before in- 

 jection. If it feels cold warm it with 

 tap water. Connect cannula with bottle 

 containing neoprene. A special appara- 

 tus for maintenance of 15tf-160 mm. Hg. 

 is advised by Lieb but it is probably 

 sufficient to provide gravity pressure 



