Life and Health 



excessive warmth. Forming more rapidly than it evapo- 

 rates, it collects in drops on the surface. 



A man's weight may be considerably 

 reduced within a few hours by means 

 of the perspiration alone. This may 

 explain to some extent the weakening 

 effect of profuse perspiration, as from 

 " night sweats " of consumption, and dur- 

 FIG. 101. Concave or ing convalescence in typhoid fever. 



Adherent Surface of 



the Nail. Experiment 86. Study the openings of the 



sweat glands with the aid of a strong magni- 

 A, border of the root ; B, 



whitish portion of semi- f y m g g lass - They are conveniently examined 

 lunar shape (the lu- on the palms, 

 nula) ; C, body of nail. 



The continuous line o 291. The Skin as a Regulator of the 

 around border repre- Temperature of the 



sents the free edge. 



Body. By means of 

 the sweat the skin performs a third, and 

 a most important, function, viz., that of 

 regulating the temperature of the body. 



The blood vessels of the skin, like 

 those of other parts of the body, are 

 under the control of the nervous system, 

 which regulates their diameter. If the FIG IQ2 NaU . n 

 nervous control be relaxed, the blood Position, 



vessels dilate, more blood flows through A, section of cutaneous 



them, and more material is brought 

 to the glands of the skin to be acted 

 upon. 



External warmth relaxes the skin and 

 its blood vessels. There results an in- 

 creased flow of blood to the skin, with 

 increased perspiration. External cold has the opposite 

 effect. 



fold (B) turned back 

 to show the root of 

 the nail; B, cutane- 

 ous fold covering tha 

 root of the nail; C, 

 semilunar whitish 

 portion (lunula) ; D, 

 body of nail 



