446 THE LIVER. 



two methyl groups, and which also contains an isopropyl group. 

 It is also generally admitted that cholesterin contains only one double 

 bond, which occurs in a vinyl group, CH:CH2, at the end. No constitu- 

 tional formula for cholesterin can be given; still there is no doubt but 

 that it is a complex terpene which stands in close relation to retene as 

 well as to the cholic acids. 



By the reduction of cholesterin by metallic sodium and amyl alcohol, DIELS 

 and ABDERHALDEN as well as NEUBERG and RAUCHWERGER obtained a dihydro- 

 cholesterin, the a-cholestanol, C 2 7H 48 0. On treating cholestenon, the ketone of 

 cholesterin, DIELS and ABDERHALDEN obtained a second dihydrocholesterin, 

 the (3-cholestanol, which WILLSTATTER and E. W. MAYER obtained directly from 

 cholesterin in ethereal solution by reduction with hydrogen and platinum-black. 

 According to DIELS and LINN x 0-cholestanol is obtained from cholestenon by 

 the action of sodium and amyl alcohol, and a-cholestanol with sodium amylate. 

 The relation of these bodies to each other is still not understood. These dihydro- 

 cholesterins have a physiological interest in regard to the question whether they 

 are identical or not with koprosterin, which will be discussed below. 



On heating cholesterin, when contaminated with iron, to 300-320, according 

 to DIELS and LiNN, 2 it in part yields cholestenon and partly an isomeric cholesterin, 

 the ^-cholesterin. This last body can be retransformed into cholesterin by the 

 saponification of the cholesteryl benzoate. 



Cholesterin occurs in small amounts in nearly all animal fluids and 

 juices. It occurs only rarely in the urine, and then in very small quanti- 

 ties. It is also found in the different tissues and organs, especially 

 abundant in the brain and the nervous system; further, in the yolk of 

 the egg, in semen, in wool-fat (together with isocholesterin), and in 

 sebum. It also appears in the contents of the intestine, in excrements, 

 and in the meconium. It especially occurs pathologically in gall-stones 

 as well as in atheromatous cysts, in pus, in tuberculous masses, old 

 transudates, cystic fluids, sputum, and tumors. It does not exist free 

 in all cases; for example, it exists in part as fatty-acid esters in wool- 

 fat, blood, lymph, brain, vernix caseosa and epidermis formations. Sev- 

 eral kinds of cholesterin, called phytosterines, have been found in the 

 vegetable kingdom. 



Cholesterin which has been crystallized from warm alcohol on cooling, 

 and also that which is present in old transudates, contains one molecule 

 of water of crystallization, and melts at 148.5 C. when' dried in a vacuum, 

 and forms colorless, transparent plates whose sides and angles frequently 

 appear broken, and whose acute angle is often 76 30' or 87 30'. In 

 large quantities it appears as a mass of white plates which shine like 

 mother-of-pearl and have a greasy touch. 



Cholesterin is insoluble in water, dilute acids, and alkalies. It is 

 neither dissolved nor changed by boiling caustic alkali. It is easily 



1 Willstatter and Mayer, Ber d. d. chem. Gesellsch., 41; Diels and Linn, ibid,, 41. 



2 Ibid., 41. 



