412 CUTIS VERA. 



The skin, thus constructed, extends over the whole of the 

 body, and is conthiued into those cavities which open upon the 

 surface, as the mouth, nose, &c., ahhough its texture changes 

 immediately upon its reflection. 



It varies in thickness in different parts ; thus, it is thicker on 

 the back than the front of the body. It is thin on the insides 

 of tlie arms and leg, where opposite surfaces touch each other.* 



It is, in general, thinner in women than in men. 



The elasticity of the skin is made evident by its yielding to 

 distention, and returning to its usual size ; as in pregnancy, 

 dropsy, &;c. ; but it is particularly demonstrated in some cases 

 of parturition, when the skin of the perinaeum stretches im- 

 mensely, and, after labor, very quickly recovers its size. 



The external surface of the skin is very generally divided 

 by superficial grooves or sulci, into sn)all spaces of various 

 angular forms ; most commonly rhomboidal. On the palms of 

 the hands and soles of the feet, instead of these figures, we 

 perceive the whole surface composed of furrows and ridges? 

 which, in some places, are rectilineal, and, in others, oval and 

 spiral. 



There are also a number of depressions or grooves which 

 seem formed to accommodate the various articulations, particu- 

 larly about the fingers and toes. 



There are other furrows, occasioned by muscles, as those on 

 the forehead ; and some depend on the subjacent cellular mem- 

 brane. 



On the external surface of the true skin, when the two 

 exterior laminae are removed, many papillae are to be seen. 

 They differ in size in different parts of the body ; they are 

 vascular, and, on the ends of the fingers, appear like villi, when 

 examined by a magnifying glass. 



There are many perforations or pores to be seen on the skin 

 with the naked eye, which are probably the ducts of sebaceous 

 glands, and the passages which transmit hairs. Other pores, 

 different from either of these, are to be seen when magnifying 

 glasses are used ; as those on the fingers ; these probably are 



* The thickness on the back, is about doable what it is on the front of the 

 body.— p. 



