tiles, the scaly skin of which is merely an epidermis whose parts are 

 much more coarsely shaped. 



It was observed (XLII.) in the account of absorption, how much fric- 

 tion facilitates the absorption of substances applied to the surface of the 

 skin, by raising the scales of the epidermis, so as to expose the orifices of 

 the absorbents, whose activity, it in other respects, increases. 



Haller conceives, that the epidermis is formed by the drying up of the 

 outer layers of the rete mucosum. Morgagni thinks it is formed by the 

 induration of the skin in consequence of the pressure of the atmosphere. 

 In objection to these hypotheses, one may inquire, how it happens, that 

 by the time the foetus, immersed in the liquor amnii, has attained its 

 third month, it is covered with such an envelope. Pressure renders the 

 skin hard and callous, increases considerably its thickness, as we see in 

 the soles of the feet and in the palms of the hands of persons engaged in 

 laborious employments. The epidermis reproduces itself with an incre- 

 dible rapidity, after falling off in scales, after erysipelas or herpetic erup- 

 tions, or, when removed, in large flakes, by blistering, it is renewed in 

 the course of a very few days. The cuticle, together with the hairs and 

 the nails, which may be considered as productions of the same substance, 

 are the only parts, in man, that are capable of reproducing themselves. 

 The hairs and the horns of quadrupeds, the feathers of birds, the calca- 

 reous matter of the lobster and of several mollusca, the shell of the turtle, 

 the solid sheaths of a number of insects, possess, as well as the epidermis, 

 this singular property. In other respects, the chemical structure of all 

 these parts is the same ; they all contain a considerable portion of phos- 

 phate of lime, withstand decomposition, and give out a considerable quan- 

 tity of ammonia, on being exposed to heat. The use of the epidermis is 

 to cover the nervous papilla?, in which the faculty of the touch essentially 

 resides, to moderate the too vivid impression that would have been pro- 

 duced by an immediate contact, and to prevent the air from drying the 

 skin, or from impairing its sensibility. 



The dessication of the cutaneous tissue is further prevented, and its 

 suppleness maintained, by an oily substance, which exudes through its 

 pores, and is apparently secreted by the cutaneous exhalants. This unc- 

 tuous liniment should not be mistaken for that which is furnished by the 

 sebaceous glands, in certain situations, as around the nostrils, in the hol- 

 low of the arm-pits, and in the groins. This adipose substance, with 

 which the skin is anointed, is abundant and fetid in some persons, especi- 

 ally in those of a bilious temperament, with red hair. It is, likewise, more 

 copious in the African negroes, as if Nature had been anxious to guard 

 against the too rapid dessication, by the burning atmosphere of tropical 

 climates. This use of the oil of the skin, is, likewise, answered by the 

 tallow, the fat, and the disgusting substances with which the Canresancl 

 the Hottentots anoint their body, in the manner described under the name 

 of tattooing, by the travellers* who have penetrated into the interior of 

 the burning regions of Africa. 



The ancients had a somewhat similar practice, and the anointing with 

 oil, so frequently used in ancient Rome, answered the same purpose, of 



* Among 1 others Kolben, Description dn Cap de Bon?ie-Es/)erance. Sparmann, Voyage 

 au Cap de Bonne F^perance et Chez fes Hottentots. Vaillant, Voyage dens PInterieur de 



