NATURAT. WAXES 327 



to bo mixtures of agnol (agnosterol), C;ioH480, and lanol (lanosterol), 

 CsoHsuO, are also present in a considerable amount. Of the common foods, 

 the most concentrated source of cholesterol is egg-yolk, in which it is 

 l^resent''^ to the extent of 1.342%. Egg-white, on the other hand, is de- 

 void of this lipoid. Certain types of gallstones are almost pure cholesterol. 



Cholesterol occurs in nature both free and in the form of esters of pal- 

 mitic, stearic, or oleic acids. That present in brain, spinal cord, gall- 

 stones, and red blood cells is in the free state, while both the ester and the 

 free alcohol are found in blood semm, as well as in the fat of the epidermis. 

 In lanolin obtained from sheep wool, the cholesterol and related sterols 

 occur exclusively as the esters. 



Although cholesterol is a constant constituent in the higher animals, it is 

 also widely distributed in the lower forms. Dor^e^^ has demonstrated 

 cholesterol in reptiles, while several investigators have shown it to be 

 present in such fishes as the mackerel, '"^"^ carp (roe^^^ and milt^®^), and sal- 

 mon.'^* Cholesterol occurs, likewise, in mollusks such as the whelk 

 (Buccinum undatwn),^^^ the octopods,'"^'^*'^ arthropods (crab),^*' annulates 

 (earthworm), ^^"^ coelenterates (sea anemone), ^^^ and in several varieties of 

 snails'^^ and shellfish. ^^^ Although Dor^e failed to detect this sterol in the 

 insects, Welsch^^^ reported its presence in the Spanish fly (Cantharis vesica- 

 toria) and in the cockchafer beetle {Melolantha vulgaris). Dor^e^^" was 

 also unable to detect cholesterol in starfish {Asterias vulgaris), but Ma- 

 thews '^^ indicated the possibility of its presence in this species; it was 

 found in the sea-urchin {Echinus), which is another echinoderm. The 

 former worker claimed that the silkworm (Bomhyx mori) contains only a 

 modified sterol, the so-called bombicesterol,^^" but cholesterol has also been 

 detected. ^^^ Apparently, cholesterol is absent from the sponges, ^®'' which 

 are on the borderline between metazoa and protozoa. However, a closely 

 allied sterol, first demonstrated by Henze^^° and called "spongosterine" 

 (spongosterol), is present in this species. The reduction product of choles- 



i6» C. Dorde, Biochem. J., 4, 72-106 (1909). 



161 M. Gobley, J. pharm. chim. [3], 17, 401-417 (1850); IS, 107-119 (1850). 



162 M. Gobley, J. pharm. chim. [3], 19, 406-421 (1851). 

 1" F. Miescher, Ber., 7, 376-379 (1874). 



'" M. Henze, Z. physiol. Chem., 55, 433-444 (1908). 



'65 A. Welsch, "Ueber das Vorkommen und die Verbreitung der Sterine im Thier- und 

 Pflanzenreich," Dissertation, Freiburg im Breisgau, 1909. Cited by C. E. Bills, Physiol. 

 /Ms., /5, 4(1935). 



'66 (". A. Ivind, S. G. Slater, and A. Vinci, J. Org. Chem., IS, 538-541 (1948). 



'6' M. Tsujimoto and H. Koyanagi, J. Soc. Chem. lad. Japan, 37, suppl., 81-85B, 

 85-86B, 436-439B (1934); 55,"ll8-120B (1935); Chem. Ahst., 28, 3257, 7566 (1934); 

 29, 3865 (1935). 



168 A. P. Mathews, /. Biol. Chem., 14, 465-467 (1913). 



"'A. Menozzi and A. Moroschi, Atti arcad. Linrei, Rend. [5], 19, 1 sem., 126-129 

 (1910). 



"6 M. ITenze, Z. physiol. Chem., 41, 109-124 (1904); 56, 427-432 (1908). 



