222 GENERAL ANATOMY. 



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turally oozes, to anoint the neighbouring skin, and principally 

 to defend it from the action of water and excrementitious hu- 

 mours. 



It is these three matters united which constitute the cutane- 

 ous excretion, an excretion that is very abundant, a part oi' 

 which is continually evaporated, while the more fixed portions 

 cover the skin, from which they are subsequently detached 

 in the form of dirt. To these excretions must be added that 

 of the epidermis, which is continually wearing away on its 

 superficial face, and is as regularly reproduced on the opposite 

 one. 



317. The skin is an organ of sensation. It is still more 

 than the other tegumentary membrane, the organ of tact, ge- 

 neral and passive, which makes us sensible of the presence of 

 bodies, their temperature, &c.; moreover, and particularly in 

 certain places, being provided with many vessels and nerves, 

 and well fitted for adaptation to the forms of bodies, it is a 

 special and active organ of touch. The tact and touch are so 

 much the more delicate, as the papillse are more developed 

 and less covered. 



318. Finally, the skin is a defensive organ, not very effi- 

 cient in man, but greatly so in particular animals, where the 

 mucous body is the seat of horny and calcareous incrustations. 

 It is evident that this organ, whose functions are as multiplied 

 as its texture is complex, can not have one of its parts or one 

 of its functions greatly developed, but at the expense of the 

 others; consequently the thicker and more protecting the 

 corpus mucosum and epidermis, the duller is the .sense of 

 touch. 



319. The embryo, until the middle of the second month, 

 has no distinct skin. About this period, according to Auten- 

 rieth, the epidermis begins to appear. Until half the term of 

 gestation, the skin remains thin, colourless and transparent: 

 it then assumes a rosy hue until about the eighth month ; at 

 this epoch it becomes pale, except in the folds. In about four 

 months and a half, the sebaceous follicles begin to be visible, 

 on the head first, and subsequently in the other parts of the 

 body : at seven months, the sebaceous or caseiform covering 



