SMEARS 



319 



SODIUM 



2-3 days. Consult Carey, E. J., Anat. 

 Rec, 1921, 21, 189-215 and Goerttler, 

 K., Morph. Jahrb., 1932, 69, 329. See 

 Chloralhydrate Maceration. 

 Smears. To examine fluids and tissues as 

 thin films so that the components are 

 individually clearly visible is often nec- 

 essary. Careful preliminary cleaning 

 of the slides is necessary. Touch the 

 surface of a slide about 2 cm. distant 

 from the end to a drop of blood imme- 

 diately on the appearance of the latter 

 from a puncture in the skin. Quickly 

 apply the smooth end of another slide 

 to the drop and the surface of the first 

 slide so that the drop spreads along the 

 line of contact. Then evenly push the 

 second slide, with the blood following it, 

 along the surface of the first slide. The 

 angle at which the pusher is held plus 

 the speed of smearing and the amount 

 of blood will determine the thickness of 

 the film. Ordinarily it should be so 

 thin that the reds are smeared in a single 

 layer. But for certain purposes as in 

 the search for some parasites thick 

 smears are the best (see Blood Smears). 



In the case of cells in cerebrospinal 

 and other fluids and of some bacteria 

 and parasites it may be desirable to 

 concentrate the objects by centrifuga- 

 tion because otherwise smears would 

 show too few of them. See Concentra- 

 tion Methods. The precautions de- 

 tailed above to obtain evenness are sel- 

 dom required. The material simply is 

 transferred to the slide in a platinum 

 loop or glass pipette and spread on it. 

 Smears of lymph nodes and spleen are 

 generally made by drawing "streaking" 

 the freshly cut, moist surfaces along 

 slides. Impression preparations of 

 these tissues are not smears but they 

 serve the same purpose. In making 

 them the surface of slide is quickly 

 pressed against the surface of the tissue 

 and a considerable number of the easily 

 detachable cells adhere to the slide 

 where they are quickly dried, or, while 

 still wet the impression can be fi.xed in 

 Helly's fluid (i.e. formalin Zenker) as 

 advised by Maximow (see Downey, p. 

 2001). McClung (p. 262) reconrimends 

 smears on cover glasses for certain germ 

 cells. 



The smears can be fixed by gentle 

 heat, or by methyl alcohol or in special 

 cases in formalin or osmic vapor. Giem- 

 sa's stain is the most popular but a 

 great many others are available es- 

 pecially for Bacteria. 



Smears cannot be made of fixed cells 

 isolated by Maceration in the same way 

 because they are not present in body 

 fluids which when they dry facilitate 

 sticking of the cells to the slides. It is 



therefore necessary to spread them on 

 slides previously moistened with a very 

 small amount of Albumen-Glycerin 

 before drying. Sec Papanicolaou Tech- 

 niques, Ear and Nasal Cell Smears. 



Smith-Dietrich method for lipoids (Die- 

 trich, A., Verb. d. Deut. Path. Ges., 

 1910, 14, 263-268). Treat frozen sec- 

 tions of formalin fixed tissues 1-3 days 

 in 5% aq. potassium bichromate at 37°C. 

 After washing in aq. dest. stain 4-5 hrs. 

 in Kultschitzky's hematoxylin (stock 

 solution 10% in abs. ale. ripened at 

 least 6 months, 10 cc. + 2% acetic acid, 

 90 cc). Wash. Differentiate over 

 night in Weigert's borax ferricyanide 

 (borax, 2 gm.; potassium ferricyanide, 

 2.5 gm. ; aq. dest., 100 cc). Wash care- 

 fully. Mount in syrup of levulose. 

 Lipoids dark blue. Lison (204) consid- 

 ers the positive staining as characteris- 

 tic for a lipine (lipoid) if the possible 

 presence of cholesterides and cholesterol 

 is excluded. 



Smooth Muscle, see Contraction Bands. 



Soap-Wax technique for paraffin imbedding, 

 see Lebowich. 



Soaps. Sodium and potassium salts of fatty 

 acids, see Fischler's modification of 

 Benda method. 



Sodium. A method for the retention of 

 sodium and potassium in microinciner- 

 ated tissue has been proposed by Poli- 

 card, A., and Fillet, D., Bull. d'Hist. 

 Appl., 1926, 230-235. In their opinion 

 these two elements are present as chlo- 

 rides in the tissue and their conversion 

 to sulphates by treating the sections 

 with sulphuric anhydride fumes makes 

 them more stable and better able to 

 withstand the high temperature of in- 

 cineration. See Microincineration Ra- 

 dioisotopes. 



A good colorimetric method for so- 

 dium is reported by Bott, P. A. (J. Biol. 

 Chem., 1943, 147, 653-661). He used 

 it for determinations of sodium in 

 glomerular urine. It works even with 

 0.3 M gm. of urine in 0.2 ^l with error of 

 about 3%. Such techniques are not 

 advised for people untrained in chem- 

 istry. 



Probably the best titrimetric method 

 for sodium is that of Linder, R. and 

 Kirk, P. L. (Mikrochemie. 1938, 23, 

 269-279) for small amounts of tissue 

 having 0.13-4.13 m gm- of sodium. Ac- 

 cording to Glick, p. 270 the technique 

 of Clark, W. G., Levitan, N. I., Gleason, 

 D. F. and Greenberg, G. (J. Biol. 

 Chem., 1942, 145, 85-100) might be 

 adapted to the required micro level for 

 histochemical investigation. 



An ultramicromethod for sodium 

 employing the polarograph has been 

 devised by Carruthers, C, Indust. and 



