336 INTEGUMENTS. 



diseased from exostosis;* and there are now in the anatomical 

 cabinet of the University, three preparations by myself of the 

 fingers of an African, where the colouring matter of the injec- 

 tion has been passed from the papillae of the cutis vera into the 

 rete mucosum ; and there deposited in dots, indicating the for- 

 mer position of the papilla?. 



SECT. III. OF THE CUTICLE (CUTICULA.) 



The Cuticle or Epidermis, is the most superficial layer of the 

 skin, and takes its wrinkles from the closeness of its applica- 

 tion to the true skin. It is a thin, dry pellicle, which cannot 

 be separated from the cutis by dissection; in consequence of 

 which we have to resort to the alternate application of hot and 

 cold water; to partial putrefaction ; or in the living body to 

 vesicatories. The mode of adhesion between the cuticle and 

 the true skin is not precisely understood: the surfaces unques- 

 tionably adhere, through the intervention of the rete mucosum, 

 with equal tenacity where there are neither hairs nor sebaceous 

 follicles to pin them together, as on the palms of the hands and 

 soles of the feet; and when by previous management this union 

 is somewhat softened, they part very much after the manner 

 of two sheets of paper, which had been recently glued and 

 were almost dry. From this it would appear that the adhe- 

 sion is universal, and not defective at any points. 



In most parts of the body the cuticle presents itself MS a sin- 

 gle homogeneal layer, of a thickness uniformly about that of 

 the thinnest Chinese blotting paper. Upon the palms and soles 

 of persons generally, but especially of such as are addicted to 

 heavy labour, and exposed to a continued mechanical irrita- 

 tion of these parts, the cuticle becomes much thickened and 

 laminated, apparently from a successive deposite of it on the 

 skin, there. It is transparent, by which the colour of the parts 

 beneath is readily discernible; in the African, however, it is 

 extremely difficult, nay, impossible to clean it wholly of the 

 colouring matter of the rete mucosum; it seems indeed as if it 

 were, according to the opinion of some, impregnated by it. 



* Mec&el speaks familiarly of its being furnished with an innumerable quanti- 

 ty of capillary vessels. Vol. i. p. 470. 



