256 ANATOMY AND PHYSIOLOGY 



renders the skin soft and pliable. Their ducts open into the de- 

 pressions (follicles) for the roots of hairs, consequently they pre- 

 serve the softness and glossiness of the hair. 



Ear wax, or cerumen, is secreted by specialized glands in the 

 auditory canal (ceruminous glands) . 



Note. The vernix caseosa which is found upon the skin of the new-born 

 child is an accumulation of sebaceous matter which has served to protect the 

 skin from the effect of long submersion in the amniotic fluid. 



The sweat glands (sudoriferous glands} are found in the skin of 

 the entire body. Each gland consists of a coiled tube embedded 

 in the corium, with a duct opening upon the surface; these ducts 

 open upon the ridges made by the rows of papillae. With an 

 ordinary magnifying glass the droplets of sweat may be seen. 



The sweat or perspiration is a thin watery fluid (highly acid, 

 but saline to the taste), containing a number of substances in solu- 

 tion, derived from the vessels in the network of the corium. The 

 most important are salt, phosphates, urea and carbon dioxide. 



It is estimated that the 2,000,000 or more glands secrete nearly 

 a liter of perspiration daily, in health. The process goes on con- 

 tinually; when the rate of excretion is moderate and uniform we 

 are not aware of it, because the moisture is removed in various 

 ways as soon as formed this is insensible perspiration. When 

 the removal does not keep pace with the production, the accumu- 

 lation on the skin becomes sensible perspiration. 



APPENDAGES OF THE SKIN 



The appendages of the skin are the glands already 'described, 

 the nails and the hairs. 



The nails are hard but elastic structures belonging to the cuti- 

 cle (being modifications of its epithelium). They give protection 

 to, and add power and ease in using the digits. The body of the 

 nail lies upon a bed of corium called the matrix, from which it 

 grows; if the matrix be destroyed the nail is lost and no new one 

 will grow in its place. The root of the nail is embedded in a fold of 

 skin; the white semicircle at the root is called the lunula (little 

 moon). 



Clinical note. The body of the nail adheres firmly to the true skin. 

 Much force is required for its removal. 



