PERSPIRATION. 



391 



tect these orifices. It is difficult to assign any special office to the hairs in some other 

 situations, but their general uses are sufficiently evident. 



Perspiration. 



In the fullest acceptation of the term, perspiration embraces the entire function of the 

 skin as an excreting organ and includes the exhalation of carbonic acid as well as of 

 watery vapor and organic matter. The office of the skin as an eliminator is undoubtedly 

 very important ; but the quantity of excrementitious matters with the properties of which 

 we are well acquainted, such as carbonic acid and urea, thrown off from the general sur- 

 face is small as compared with the amount exhaled by the lungs and discharged by the 

 kidneys. If the surface of the body be covered with an impermeable coating, death 

 occurs in a very short time ; but the phenomena which precede the fatal result are diffi- 

 cult to explain. All that we can say upon this point is that death takes place when the 

 heat of the body has been reduced to about 70 Fahr., and that suppression of the 

 function of the skin in this way is always followed by a depression of the animal tem- 

 perature. The cause of death has never been satisfactorily explained, partly for the 

 reason that we are unacquainted with the nature and properties of all the excrementitious 

 matters exhaled from the skin ; and it is not easy to understand why coating the surface 

 should be followed by such a rapid diminution in the general temperature. The experi- 

 mental facts, however, indicate that the skin probably possesses important functions with 

 which we are entirely unacquainted. Physiological chemists have detected urea and some 

 other effete matters in the perspiration, but it is probable that some volatile principles 

 are eliminated by the general surface, which have thus far escaped observation. 



Sudoriparous Glands. The most numerous and the most important glands of the 

 skin are those which secrete the sweat. The other glands, which have been already 

 considered, have rather a mechanical function, serving to keep the skin and its append- 

 ages in a proper condition for the protection of the subjacent parts ; but it is the perspir- 

 atory apparatus chiefly which is concerned in the great function of elimination. 



With few exceptions, every portion of the skin is provided with sudoriparous glands. 

 They are not found, however, in the skin covering the concave surface of the concha of 

 the ear, the glans penis, the inner lamella of the prepuce, and, unless the ceruminous glands 

 be regarded as sudoriparous organs, in the external auditory meatus. 



On examining the surface of the skin with a low 

 magnifying power, especially on the palms of the 

 hands and the soles of the feet, the orifices of the 

 sudoriferous ducts may be seen in the middle of the 

 papillary ridges, forming a regular line in the shal- 

 low groove between the two rows of papilke. The 

 tubes always open upon the surface obliquely. If 

 a thin section of the skin be carefully made and 

 examined microscopically, the ducts are seen pass- 

 ing through the different layers and terminating 

 in rounded, convoluted coils in the subcutaneous 

 structure. These little, rounded or ovoid bodies, 

 which constitute the sudoriparous, or sweat-pro- 

 ducing apparatus, may be seen attached to the un- 

 der surface of the skin, when it has been removed 

 from the subjacent parts by maceration. The per- 

 spiratory apparatus consists, indeed, of a simple 

 tube, presenting a coiled mass beneath the skin, the 

 sudoriparous portion, and a tube of greater or less length, in proportion to the thickness 

 of the cutaneous layers, which is the excretory duct, or the sudoriferous portion. 



FIG. 111. Surface of the palm of the Jianrf ; 



a portion of the *kin attout one-lmlf 



an inch squwe, magnified 4 diameters. 



(Sappey.) 

 1, 1, 1, 1, openings of the sudoriferous ducts; 2, 



2 2, 2, grooves between the papilla) of the 



skiii. 



