GROUP OF THE CUTANEOUS SECRETIONS 895 



the roots of the larger hairs. Their ducts open directly into their 

 sheath. But the other regions of the skin are not free from them; in 

 fact, many of them contain them in large numbers, their excretory ducts 

 then opening free upon the surface. They are especially numerous 

 upon the forehead, nose and back; but are absent from the volamanus 

 and planta pedis. Closely related to these glands are those of the labia 

 minora, glans penis, and prepuce as well as the ceruminous glands of 

 the external auditory meatus. The acini of these structures are 

 packed with polyhedral and flattened cells which divide and gradually 

 move outward in successive layers, where they disintegrate in the 

 oily semi-liquid secretion filling the duct. In this way, a fatty ma- 

 terial is formed which on exposure to the air assumes a cheesy consist- 

 ency. When the ducts of these glands become blocked, this material 

 undergoes retrogressive changes and then forms a fertile medium 

 for the growth of the ordinary pus-microbes. 



The exact composition of this secretion is not known. It contains 

 fats, soaps, cholesterin, albuminous material, remnants of epithelial 

 cells and inorganic salts. 1 The cerumen or ear-wax contains a 

 reddish pigment and possesses a bitter-sweet taste. Similar materials 

 are the smegma praeputii and the fatty and odoriferous secretions of 

 the anal and uropygal glands of many animals. The sebaceous material 

 which is generally found upon the skin of the newborn infant, is known 

 as vernix caseosa. 2 Its distribution alone would indicate that it 

 possesses a manifold function. Thus, it may rightly be concluded that 

 it serves to lubricate the surface of the skin and to protect the hairs 

 against drying. Moreover, since it is spread out in an almost continu- 

 ous layer across the skin, it aids in retaining the body-heat and plays, 

 therefore, an important part in regulating the body-temperature. 

 This fact is clearly recognized by the northern races, such as the Esqui- 

 maux, because they carefully preserve this secretion and even inten- 

 sify its action by anointing their bodies with fatty substances. In 

 the aquatic animals it serves a twofold purpose, because it protects them 

 against any undue loss of heat and diminishes the friction between 

 their integument and the water. Lastly, the modified secretions of 

 the anal, uropygal, and sexual glands of many animals no doubt play 

 an important part in the production of- the sexual reflexes. 



The sweat-glands are simple tubular in character and consist of a 

 coiled up portion which occupies the deeper layer of the skin, and a 

 long winding duct which penetrates the corium and epidermis and 

 eventually terminates in a funnel-shaped enlargement upon its surface. 3 

 They are found in especially large numbers upon the palms of the 

 hands, the soles of the feet, in the axilla, groin and upon the forehead, 

 but are absent from the glans penis, prepuce and the margins of the 



1 Linser Dissertation, Tubingen, 1904. 



2 Zumbusch, Zeitschr., ph. Chemie, LIX, 1909, 506. 



3 Rabl (Histology of the Sweat-Glands) in Handb. der Hautkrankheiten, 

 Wien, 1901. 



