CHEMICAL NATURE OF SKIN SECRETIONS. 675 



Sotnitschewsky, 1 in an analysis of a dermoid cyst of the ovary, found 

 tripalmitin, tristearin, and trioleiii ; soaps of the acids of these fats and 

 of caproic and caprylic acids, albumin, cholesterin, and an alcohol of 

 high molecular weight, which, however, was not cetyl alcohol.' 2 Tyrosiiie, 

 hypoxanthin, xanthin, sugar, and glycogen were absent. 



The vernix caseosa of man, according to Ruppel 3 and Liebreich, 4 con- 

 tains cholesterin fats of oleic and palmitic acids, as well as glycerin fats, 

 and also free cholesterin and isocholesterin. 



The cerumen of the ear has been investigated by Petrequin, 5 and is 

 found to contain potash soaps of oleic and stearic acids in the case of man 

 and the ox, while in the dog the base is lime, and in the horse magnesia. 



Wool fat, the sebaceous secretion of the sheep's skin, was proved by 

 Hartinann to contain no glycerin fats, but only those with cholesterin 

 as alcohol. Schulze and Urich 7 confirmed this, and also found free 

 cholesterin and isocholesterin. 



These cholesterin fats (so-called " lanoline ") have been specially 

 investigated by Liebreich, 8 who finds that they are associated with 

 keratinised structures, and are not necessarily formed in sebaceous 

 glands, but may be formed within epidermic cells. Tortoiseshell, whale- 

 bone, horn, quills of porcupine and hedgehog, hoof of horse, and beak of 

 crow, all contain these fats. The skin of the two-toed sloth has no sebace- 

 ous glands, and yet contains cholesterin fats, while pigeons bereft of 

 their uropygial glands still have these substances in their feathers. 



Such fats are peculiar, in that they can take up more than their weight 

 of water, and also in that they do not become rancid, and offer a 

 complete protection against the entrance of micro-organisms. Liebreich 

 compares them to the wax of plants, which is an ether of a monohydric 

 alcohol with a fatty acid. 9 



The secretion of the tail gland of the bird 10 has been chemically investi- 

 gated by de Jonge. 11 



The secretion contains cetyl alcohol, the alcohol of spermaceti. No sugar 

 or urea is present. Geese deprived of the tail gland and immersed in water are 

 found to take up from two to two-and-a-half times as much water in their 

 plumage as normal birds. 12 



The so-called "pigeons' milk," with which the young birds are fed by both 

 parents during the earlier days of life, is practically a sebaceous secretion of 

 temporary glands formed in the lateral pouches of the crop in both cock and 



1 Ztschr. f. physiol. Chem., Strassburg, 1880, Bd. iv. S. 345. 



2 Ernst Ludwig (Ztschr. f. physiol. Chem., Strassburg, 1897, Bd. xxiii. S. 38) has quite 

 recently found cetyl alcohol in the contents of dermoid cysts of the ovary. 



* lUd., 1895, Bd. xxi. S. 122. 

 "Verhandl. d. Berl. physiol. Gesellsch.," in Arch. f. Physiol., Leipzig, 1890, S. 363. 



5 Gompt. rend, Acad. d. sc., Paris, 1869, tome Ixix. p. 987 ; also 1869, tome Ixviii. 

 p. 940 ; Jahresb. ii. d. Fortschr. cL Thier-Chem., Wiesbaden, 1871, Bd. i. S. 36 ; 1874, 

 Bd. ii. S. 33. 



6 Inaug. Diss., Gottingen, 1868. 



7 Ber. d. deutscli. chem. Gesellsch., Berlin, 1872, Bd. v. S. 1075 ; 1874, Bd. vii. S. 570. 



8 Berl. klin. Wchnschr., 1885, Bd. xlvii. S. 761 ; Compt. rend. Acad. d. sc., Paris, 1888, 

 tome cvi. p. 1176 ; and "Verhandl. d. Berl. physiol. Gesellsch.," in Arch. f. Physiol., 

 Leipzig, 1890, S. 363. 



9 The secretion of the Harderian gland of the orbit of rodents, though fatty in nature, is 

 not formed by disintegration of cells ; Wendt, r '"freber die Harder'sche Druse," Strassburg, 

 1877 ; Kamocki, Biol. Centralbl., Erlangen, Bd. ii. S. 709. 



10 For anatomy, see Robby Kossmann, Ztschr. /. ivissensch. Zool., Leipzig, 1871,' Bd. 

 xxi. S. 568. 



11 Ztschr. f. physiol. Chem., Strassburg, Bd. iii. S. 225. 

 13 Max Joseph, Arch. f. Physiol. Leipzig, 1891, S. 81. 



