284 FATTY SUBSTANCES 



if the sections are turned over after fifteen minutes in (C). (8) For 

 an indication of the results obtainable see the coloured plate 

 published by Whitehead (1935). 



THE SCHULTZ CHOLESTEROL TEST 



662. Principle. The Schultz cholesterol test is an application to 

 histological sections of the Liebermann-Burchardt cholesterol test 

 (Schultz, 1924-25 ; Schultz and Lohr, 1925 ; Schultz, 1925). 

 The colour reaction is said to be due, not to cholesterol itself, but 

 to some product of its oxidation, termed oxycholesterol (Windaus, 

 cited by Schultz, 1925). The reaction was originally obtained after 

 exposing sections to strong light, but treatment with metallic 

 salts, especially iron alum, was found to be equally effective. 

 When a mixture of glacial acetic and sulphuric acids is added to a 

 treated section, the development of a blue-green colour indicates 

 that cholesterol was present in the section before it was treated. 



663. Specificity. Kimmelstiel at first doubted (1925), but later 

 admitted (1927), the specificity of the reaction. The conclusions 

 of Schultz were supported by Arndt (1925), Laux (1926) and 

 Mayer (1928), and confirmed completely by Kaufmann and 

 Lehmann (1926 a, h). They applied the test to 109 substances 

 and found that the result was never positive in the absence of 

 cholesterol although it might be negative even when cholesterol 

 was present. Cholesteryl stearate, for example, gave a negative 

 result, and mixtures containing it gave positive results only if 

 cholesterol itself was among the ingredients. Since cholesterol 

 by itself gives a positive result (after preliminary treatment) its 

 presence would explain the positive result with such a mixture. 

 The results with the following mixtures (Kaufmann and Lehmann, 

 1926 h) are instructive. Cholesterol-lecithin + ; cholesterol- 

 lecithin-glycerin — ; cholesterol-lecithin-glycerin-stearic acid +. 

 Glycerin thus inhibited the reaction, but its effect was annulled if 

 stearic acid was present. These examples suggest that a negative 

 result in histological sections may be due to many causes. 



In animal tissues a positive result is specific for cholesterol, 

 whether in the free or ester form, because no other sterol is 

 present in significant amounts. In plant tissues substances other 

 than sterols and their esters might give a positive result. 



664. Technique. The following solutions are needed : 



(A) \0 per cent, solution of iron alum. Dissolve at room tempera- 

 ture 100 g. violet iron alum, (NH4)2S04 . Fe2(S04)3 . 24H2O, in 

 distilled water and make up volume to 1 litre. (B) 2-5 jjer cent, 

 solution of iron alum. Dilute 1 volume of (A) to four times its 

 volume with distilled water. (C) Acid mixture. Add slowly, with 

 external cooling, concentrated sulphuric acid to an equal volume 

 of glacial acetic acid. Formol-fixed frozen sections are : (1) Placed 



