260 THE HUMAN SKIN. 



nious anatomist, that in a square inch of skin there is a length of 

 tubing of 73 feet, or in the whole body, of 28 miles; this vast 

 drain-work being intended to conduct effete materials from the 

 system. Every organ is engaged night and day in sweating them 

 out, through passages more or less circuitous, to the border shores 

 of the skin. What is the nature of this large clearance of goods ? 

 or what is its common source ? 



The blood is the origin of the sensible perspiration, which com- 

 prises both the watery matter given off by the perspiratory glands, 

 and the unctuous moisture which oozes from the sebaceous follicles. 

 This is shown by the fact that the skin, and especially its glands 

 and follicles, are beset with sheets of capillaries ; and the fat itself, 

 which furnishes the matter to the sebaceous follicles, is a deposit 

 from the blood. The rule is, that the blood all over the system is 

 constantly sent to the frontier, and its useless portions, averse to the 

 life and movements of the rest, are let out through the skin, in 

 obedience to their own unsocial tendency; the skin itself regulating 

 their escape, and preventing the life of the body from being led 

 away at the same time with the worn-out or ill-affected perspirations. 

 This is shown to be the case in health by what takes place in disease, 

 as well as during fear and other mental emotions, in which the proper 

 constraint is not employed by the skin, and the living essences them- 

 selves run away in crowds from the irritated and incontinent blood-ves- 

 sels. As in other parts of the capillary system, the nervous fibres are 

 the intelligent agents of the above elimination, and governing, that is, 

 opening and shutting the pores, from the minute doors of the blood- 

 vessels to the wide avenues in the skin, they grant or refuse passports 

 to the various applicants that incline to go out into the world. This 

 office of the nerves is seconded by the mechanism of the parts, for 

 the perspiratory and sebaceous ducts rise from the convoluted glands 

 in spiral turns through the layers of the skin, and their orifices also 

 exhibit the law of the spiral pathway, and are half-closed by the 

 cuticle, which shuts down upon them like a lid, from under which 

 the perspiration escapes obliquely, by overcoming its gentle force ; 

 exsinuation and insinuation being the methods of this commonwealth. 

 The cutaneous exhalation is reckoned at nearly 30 ounces per day, 

 which is supposed to be about twice the average quantity of matter 



