SHANKLIN 



314 



SILVER CITRATE 



height of the filament and the distance 

 from filament to specimens determine 

 the casting angle. Both an oil-diffu- 

 sion pump and a mechanical pump must 

 be used to produce the degree of vacuum 

 required (at least ICT* mm. Hg.). With 

 a suitable vacuum provided, the fila- 

 ment is heated electrically and a meas- 

 ured weight of metal is vaporized. 

 Preparations are then ready for mount- 

 ing or examination. A figure of the 

 apparatus and the formula for calcu- 

 lating the appropriate mass of metal for 

 the conditions of shadowing are pre- 

 sented in the Dempster and Williams 

 paper. Wyckoff's book (above) covers 

 completelj' applications to electron 

 microscopy. 



Shanklin, see Pineal, Silver Diaminohy- 

 droxide after sensitizing with sodium 

 sulfite. 



Sharpening, see Microtome Knife. 



Shrinkage caused by fi.xation, dehydration 

 and clearing of nervous tissues has been 

 measured by King, H. D., Anat. Rec, 

 1910, 4, 213-244 and by Allen, Ezra, 

 Anat. Rec, 1916, 10, 565-589. 



Sickle-Cell Trait. A critical study of 

 methods for detection by Diggs and 

 Pettit (L. W. and V. D., J. Lab. & Clin. 

 Med., 1939, 25, 1106-1111) gives first 

 place to the Moist Stasis technique of 

 Scriver and Waugh. Place a rubber 

 band about proximal part of a finger. 

 Leave 5 min. Puncture and examine 

 fresh blood for sickle cells. According 

 to Hansen-Pruss (O. C, J. Lab. & Clin. 

 Med., 1936-37, 22, 311-315) the maxi- 

 mum percentage of sickle cells is 

 produced in 4-5 hrs. by supravital 

 staining with brilliant cresyl blue or 

 janus green, while it takes 24 hrs. in 

 unstained moist preparations. 



The following rapid method of diag- 

 nosis is reported by Neuda, P. M. and 

 Rosen, M. S., J. Lab. & Clin. Med., 

 1945, 30, 456-458. Mix "cherry -size" 

 piece of feces with 5 cc. isotonic sodium 

 chloride solution. Add 0.1 cc. of fil- 

 trate to tube of nutrient broth, incubate 

 24 hrs. at 37°C. To top of suspected 

 blood on slide add drop of culture. 

 Something in broth makes susceptible 

 cells quickly assume sickle form. 



Siena Orange (K. Hollborn, Leipsig) = 

 sodium paradipicrylamine, an alleged 

 stain for potassium (Carere-Comes, O., 

 Zeit. wiss. Mikr., 1938, 55, 1-6). 



Silicon. Easily recognizable in sections 

 viewed in polarized light. It often 

 occurs as sericite in combination with 

 magnesium, iron and other minerals, see 

 Jones, W. R.,J. Hyg 1933, 33, 307-329. 

 Microtechnique is discussed by Poli- 

 card, A., and Mastin, E., Bull. d'Hist. 

 Appl., 1933, 10, 22-36. Microincinera- 



tion is useful but Scott says that an 

 exaggerated idea of amount may be 

 obtained (McClung, p. 659). 



Sintered-glass filters, see Cunningham, 

 B., Kirk, P. L. and Brooks, S. C, J. 

 Biol. Chem., 1944, 139, 21-28. 



Silver is occasionally found in the tissues 

 particularly after treatment with silver 

 nitrate or argyrol. It appears as brown 

 to black granules or masses, is definitely 

 blackened by ammonium sulphide and 

 may be removed by a mixture of sodium 

 thiosulphate and potassium ferri- 

 cyanide solutions. Recently a method 

 based on reaction between silver and p- 

 dimethylaminobenzylidenrhodanin has 

 been described and illustrated in colors 

 (Okamoto, K., Utamura, M. and Akagi, 

 T., Acta Scholae Med. Univ. Imp. in 

 Kioto, 1939, 22, 361-372). Details are 

 supplied by Glick, p. 26. 



Silver Chloride Dichlorfluoresceinate 

 coloration of vascular endothelial cells 

 (Bensley, R. D. and S. H., Anat. Rec, 

 1935, 64, 46-49). Inject intravenously 

 0.8% aq. dichlorfluorescein until animal 

 becomes quite yellow. Kill animal: 

 remove tissues and immerse in 10% 

 aq. silver nitrate or in Bensley's Silver 

 Citrate solution until salmon pink color 

 develops. Fix in 10% neutral formalin. 

 Dehydrate in alcohol and Iso-Safrol, 

 clear in iso-safrol and mount in balsam. 

 Endothelial cells outlined in pink. On 

 exposure to light color changes in time 

 the silver becoming brown and black. 

 See demonstration of Chlorides in lungs 

 by this method. 



Silver Citrate injection of blood vessels 

 (Bensley, R. D., Am. J. Anat., 1929, 

 40, 146-169). This method has proved 

 of great value in the investigation of 

 efferent vessels of renal glomeruli. It 

 can be employed to advantage in other 

 situations particularly in association 

 with supravital staining of Pericapillary 

 Cells with janus green. To make up 

 the solution dissolve 4 gm. silver nitrate 

 in 100 cc. aq. dest. and remove to dark 

 room. Completely precipitate silver 

 as silver phosphate by addition of 

 sodium phosphate solution. Wash ppt. 

 repeatedly with aq. dest. decanting 

 supernatant fluid. Make up to volume 

 approximately 30 cc. Dissolve ppt. by 

 adding 28 cms. pure citric acid (or 

 tartaric acid) in crystals. Dilute with 

 aq. dest. to 1000 cc. and keep in dark. 



For use, dilute this stock solution 

 with 3 times its volume 1% aq. sodium 

 citrate. Kill the animal by bleeding. 

 For kidneys and other abdominal 

 viscera insert into aorta cannula con- 

 nected by rubber tubing with pressure 

 bottle. First perfuse with 1% aq. 

 sodium citrate with the pressure bottle 



