TOUCH. 379 



lated to afford protection to the finely organized 

 coriiim. 



Although the cuticle exhibits no traces of vas- 

 cularity, it is by no means to be regarded as a 

 dead or inorganic substance, like the shells of 

 the mollusca. That it is still part of the living 

 system is proved by the changes it frequently 

 undergoes, both in the natural and the diseased 

 conditions of the body. It is perpetually, though 

 slowly, undergoing decay and renovation ; its 

 external surface drying off in minute scales, 

 and in some animals peeling off in large por- 

 tions. When any part of the human skin is 

 scraped with a knife, a grey dust is detached 

 from it, which is found to consist of minute 

 scales. 



By repeated friction, or pressure of any part 

 of the skin, the cuticle soon acquires an increase 

 of thickness and of hardness ; this is observable 

 in the soles of the feet, and palms of the hands, 

 and in the fingers of those who make much use 

 of them in laborious work. But this greater 

 thickness in the parts designed by nature to 

 sufier considerable pressure, is not entirely the 

 effect of education ; for the cuticle, which exists 

 before birth, is found even then to be much 

 thicker on the soles of the feet, and palms of the 

 hands, than on other parts. This example of 

 provident care in originally adjusting the struc- 

 tures of parts to the circumstances in which 



