14-8 INTRODUCTION. 



plough, it acquires, by continued friction, an almost horny texture. It 

 is capable of being raised by a blister, or by scalding water, from the 

 subjacent parts, and is, itself, insensible, being destitute of nerves : 

 indeed, neither these, nor vessels or tubes of any kind, enter into its 

 composition : it is neither fibrous, cellular, nor laminated, but would 

 appear to be formed by the hardening of the superficies of the mucous 

 surface beneath. It is, in fact, extra-organic, a sort of natural garment, 

 designed as a defence to the tender surface of the cutis, and as a pre- 

 ventive of the pain, which would otherwise be produced by the actual 

 contact of even the air with the nervous papillae. We know how 

 sensitive the denuded skin is, when abraded by a blister ; how pain- 

 ful the least touch ; nay, how distressing a sensation a cold and 

 drying air will occasion ; and how the system sympathizes with the 

 irritation of the nervous papillae. Were it not for the epidermis, we 

 should not be able to use our hands as organs of touch ;* and, without 

 it, our bodies, subjected to the " rude elements" around us, would thrill 

 with agony. 



The epidermis is most accurately adapted to the cutis : it invests 

 the nervous papillae ; it admits the egress of the hairs ; it is perforated 

 by the minute exhalant tubes of the capillary vessels, the fine ducts of 

 the cutaneous or sebaceous follicles, and the orifices of the absorbents ; 

 yet it prevents the evaporation of the mucus, or of the moisture of the 

 c'utis, the softness and flexibility of which it duly preserves. The 

 beautiful lines which it presents on the palms, and on the tips of the 

 fingers, and the soles of the feet, are well known. 



Where the body is covered with fur, as in most of the lower Mamma- 

 lia, the epidermis is often very thin, and, in some animals, it is so easily 



separable after death, that their 

 skins are not to be preserved, 

 with the fur attached, without 

 difficulty; and it always be- 

 comes separated upon the com- 

 mencement of the putrefactive 

 process, slipping from the skin 

 in shreds. 



On the dense, rough, naked 

 hide of the Elephant and the Rhinoceros, the cuticle is thick, and, in some 

 parts, almost horny, or studded with horny tubercles. On the tail of the 

 Beaver (fig. 148), the Rat, the Opossum, &c., it is semitransparent, and re- 



* Shakspere observes, "The hand of little employment hath the daintier sense." (Hamlet.) Where 

 the epidermis is preternaturaHy thickened by hard labour, it is too complete a barrier between external 

 objects and the nervous papillae, and prevents accuracy or delicacy of touch ; it materially intercepts 

 the impression of agents upon the organs of the sense of feeling. 



