326 PHYSIOLOGICAL CHEMISTRY. 



Sebum, when freshly secreted, is an oily semi-fluid mass which 

 solidifies on the upper surface of the skin, forming a greasy coating. 

 The quantity is very different in different persons. HOPPE-SEYLER 

 has found a body similar to casein, besides albumin and fat, in the 

 sebum. Cholesterin is also found in this fat, and in especially large 

 quantities in the vernix caseosa. The solids of the sebum consist 

 chiefly of fat epithelium-cells and protein bodies; the vernix case- 

 osa consists chiefly of fat. 



Cerumen is a mixture of the secretion of the sebaceous and 

 sweat glands of the cartilaginous part of the outer organs of hear- 

 ing. It contains chiefly soaps and fat, and besides these a red sub- 

 stance easily soluble in alcohol and with a sweetish-bitter taste. 



The preputial secretion, smegma praputii, contains chiefly fat, 

 also cholesterin and ammonium soaps, which probably are produced 

 from decomposed urine. The hippuric acid, benzoic acid, and cal- 

 cium oxalate found in the smegma of the horse have probably the 

 same origin. 



We may also consider as a preputial secretion the castoreum, which is 

 secreted by two peculiar glandular sacks in the prepuce of the beaver. Thi& 

 castoreum is a mixture of proteids, fat, resins, traces of phenol (volatile oil), 

 and a non-nitrogenized body, castorin, crystallizing in four-sided needles from 

 alcohol, insoluble in cold water, but somewhat soluble in boiling water, and 

 whose composition is little known. 



Wool-fat, or the so-called fat-sweat of sheep, is a mixture of the secretion of 

 the sudoriparous and sebaceous glands. We find in the watery extract a large 

 quantity of potassium which is combined with organic acid, volatile and non- 

 volatile fatty acids, benzoic acid, phenol-sulphuric acid, lactic acid, malic acid, 

 succiuic acid, and others (BuisiNE). The fat contains among other bodies 

 abundant quantitiesof ethers of fatty acids with cholesterin and isocholesteriu. 



WEBER found that from the glands of the skin of a kangaroo and a dwarf- 

 antelope a colorless secretion was eliminated which in the first case, when ex- 

 posed to the air, formed a red and in the second case a blue coloring matter. 

 The secretion of the coccygeal glands of ducks and geese contains a body sim- 

 ilar to casein, besides albumin, nuclein, lecithin, and fat, but no sugar CDs 

 JONGE). Poisonous bodies have been found in the secretion of the skin of the 

 salamander and the toad, respectively, samandarin (ZALESKY) and bufidin(Jon~ 

 NARA and CASALI). 



The Sweat. A disproportionally large part of the secretions of 

 the skin whose quantity amounts to about -fa of the weight of the 

 body consists of water. Next to the kidneys the skin is the most 

 important means for the elimination of water. As the glands of 

 the skin and the kidneys stand near to each other in regard to 



