260 



plied to polished surfaces, and to discover the slightest asperites* I have 

 observed the sense of touch to be very imperfect, in men wasted by ma- 

 rasmus, and whose hard, dry, and wrinkled skin adheres, in certain si- 

 tuations, to the subjacent parts. 



The chemical analysis of the cutaneous tissue shows, that it does not 

 exactly resemble that of the cellular and membranous tissue ; it is gela- 

 tino-fibrous, and, with regard to its structure and to its share of contrac- 

 tility, it occupies a medium, between the cellular tissues and the muscular 

 flesh*. There arise, from the surface of ihe skin, innumerable small 

 papillae, fungous, conical, pointed, obtuse and variously shaped, in the 

 different parts of the body. These papillae are merely the pulpous extre- 

 mities of the nerves which terminate into them, and around which there 

 are distributed vascular tissues of the utmost minuteness. The papillae 

 of the skin, which are more distinct in the fingers and lips than else- 

 where, swell, v/hen irritated, elevate, in a manner, the epidermis, and 

 this kind of erection, which is useful when we wish to touch a substance 

 with great precision, may be excited by friction or by moderate heat. 



The nervous or sentient surface of the skin is covered with a mucous 

 coating, colourless in Europeans, of dark colour, from the effects of light, 

 among the natives of southern climates 5 of a gelatinous nature, destined 

 to maintain the papillse in that state of moisture and softness favourable 

 to the toucfc. This mucilaginous layer, known under the name of ret-e 

 mucosu?n of Malpighi, seem to contain the principle which causes the va- 

 riety of colour in the skin of different nations, as will be observed, in 

 speaking of the varieties of the human species. 



The reticular state of the rete mucosum may be explained in two ways; 

 a thin and gelatinous layer, extending on the papillar surface of the skin, 

 is perforated, at each nervous papilla; and if it were possible to coagulate 

 or to detach this coating, we should have a real sieve, or reticulated mesh 

 work, _with a perforation at every point, corresponding to a cutaneous pa- 

 pillse. The sanguineous and lymphatic capillaries, which surround the 

 nervous papillse, form, besides, by their connexions, a net-work, the 

 meshes of which are very minute and adhere to the epidermis, by a mul- 

 titude of small vascular filaments that insinuate themselves between the 

 scales of this last envelopef. 



The skin would be unable to perform its functions, if an outer, thin, 

 and transparent membrane, the ejiidcrmis^ did not prevent it from being 

 over dried. This superficial co^ring is quite insensible, no nerves and 

 no vessels, of any kind, are found in it, and even in the present state of 

 science, we do not understand how it is formed, how it repairs and repro- 

 duces itself when destroyed. The most minute researches on its struc- 

 ture, merely show the existence of an infinite number of lamellae, lying 

 over each other, and overlapping each other, like the tiles of a roof. This 

 imbrication of the epidermoid lamellae, is very obvious in fishes and rep- 



* See the Chapter in the APPENDIX, on the chemical constitution of the animal tex- 

 tures and secretions. Copland. 



| And terminate in exhaling or absorbing- pores, according as they belong- 

 to the arterial capillaries, or Jto the lymphatic absorbents. It is sufficient, indeed, to 

 remove gently the scales of the epidermis, in order to bear their orifices and procure 

 the absorption of any virus. It is the net-work of MALPIGHI, or rather this assemblage 

 of interlaced capillary vessels below the epidermis, which appears to be the seat of the 

 primary phenomena iji the majority of cutaneous inflammations and eruptive diseases. r_ 

 Copland. 



