SOLID GREEN O 



228 



SPHINGOMYELIN 



Solid Green O, see Malachite Green. 

 Soluble Blue 3M or 2R, see Anilin Blue. 

 Soluble Indulin 3B, see Indulin, water 



soluble. 

 Soluble Yellow OL, see Metanil Yellow. 

 Solutions. In technique several kinds are 



employed. 



1. Physiological solutions are in- 

 tended to approximate as closely as 

 possible to the tissue fluid environments 

 of cells so that cells examined in them 

 will not be greatly altered thereby. 

 See Physiological Solutions. 



2. Normal solutions are, on the other 

 hand, chemical standards made by dis- 

 solving definite amounts of substance 

 (easily calculated) in sufficient aq. dest. 

 to make 1 liter. See Normal Solutions. 



3. Molar, molecular and grammolecu- 

 lar solutions contain the molecular 

 weight of the substance in grams per 

 liter. They are of the same concentra- 

 tion as normal solutions of substances 

 possessed of one hydrogen or other 

 equivalent and differ from those of sub- 

 stances containing more than 1 such 

 equivalent. See Molecular Solutions. 



4. Molal solutions contain the molec- 

 ular weight of the substance in grams 

 + 1000 grams aq. dest. The designa- 

 tion molal is rarely used, molecular is 

 common and normal most frequent. 



Sonic Vibrations. Employed as a means for 

 fractionating spermatozoa so that their 

 several parts can later be collected by 

 centrifugation (Zittle, C. A. and O'Dell, 

 R. A., J. Biol. Chem., 1941, 140, 899- 

 907). 



Sorensen's Buffers. Sorenson's phosphate 

 buflfers are prepared from Merck's 

 special reagents. Dry salts at 105 °C. 

 overnight and store in a dessicator over 

 CaCh. M/15 solutions are used. To 

 make them dissolve the following 

 amounts in aq. dist. and make each so- 

 lution up to one liter: 



NatHPO* anhydrous 9.47 gm. 



KH2PO4 9.08 gm. 



To obtain a solution of the pH re- 

 quired, mix them in following amounts : 



For range pH 8.2-9.2 see Palitzsh Buf- 

 fers. See affect of Phosphate Solutions 

 on living cells. 



Spalteholz Method for clearing small em- 

 bryos as suggested by the Bensleys. 

 After appropriate fixation 80 and 95% 

 alcohol 1 day each. Two changes ab- 

 solute alcohol, 2 days. Equal parts 

 benzol and absolute alcohol, 1 day. 

 Two changes pure benzol, 1 day. Then 

 Wintergreen oil (methyl salicylate) and 

 benzyl benzoate by weight 5:1, 3:1 and 

 2:1 for very young, young and older 

 embryos respectively (under negative 

 pressure in vacuum pump) until cleared. 

 Mount or store in this clearing fluid. In 

 practice it is possible to get good results 

 without the negative pressure. This 

 method can be used for many tissues 

 besides embryos. For author's account 

 see Spalteholz, W., Ueber das Durch- 

 sichkigmachen von menschlichen und 

 Tierischen Praparaten. Leipzig, 2nd 

 Edition, 1914. 



Specific Gravity. It is often desirable to 

 ascertain the relative specific gravities 

 of tissues, cells and parts of cells. See 

 Centrifugation. 



Spectrographic Analysis, see Histospectro- 

 graphy and Absorption Spectra. 



Spectrophotometric Analysis of tissue stain- 

 ing has been greatly advanced by 

 Stowell, R. E. and Albers, V. M., Stain 

 Techn., 1943, 18, 57-71. Comparison 

 of spectral absorption curves of stains 

 and substances colored by them has 

 demonstrated that data can thereby be 

 obtained on the chemical processes in- 

 volved. No evidence was found of sig- 

 nificant chemical alterations in the 

 chromophox radicals of the stains asso- 

 ciated with the tissue staining under the 

 conditions of the experiments. 



Spectrophotometric Evaluation of blood 

 stains (Lillie, R. D. and Roe, M. A., 

 Stain Techn., 1942, 17, 57-63). 



Spermatozoa, simple method for staining. 

 IVIake smears of fresh spermatic fluid on 

 slides and dry in air. Fix 3 minutes in 

 10% formalin. Stain in Harris' hema- 

 toxylin 1 minute, wash in water and dry 

 (Fetterman, G. H., Am. J. Clin. Path., 

 1942, 6, 9). Microincineration (Poli- 

 card. A., Bull. d'Hist. AppL, 1933, 10, 

 313-320). Helpful histochemical meth- 

 ods are detailed by Marza, V. B., 

 Bull, d'hist. appl., 1931, 8, 85-102. See 

 Semen. 



Spermin Crystals are long prism-like forma- 

 tions produced in dried semen colored 

 brown or violet with iodine or potas- 

 sium iodide, also known as Boettcher's 

 crystals. 



Sphingomyelin, a compound of phosphoric 

 acid, a fatty acid, choline and sphingo- 

 sine without glycerol, soluble in ben- 

 zene, pyridine and hot alcohol and al- 

 most insoluble in ether, see Lipoids. 



