216 GENERAL ANATOMY. 



nished with vessels, and that it is nourished by intus-suseep- 

 tion. Mojon, like Klinkosch, supposes it to contain fibres, 

 lamina, vessels, and all the properties of organization, and of 

 life. Mascagni considers it as being entirely formed of ab- 

 sorbent vessels. Fontana had previously thought he saw spiral 

 vessels in it, but M. de Humboldt found these supposed ves- 

 sels were nothing more than folds. The most attentive ex- 

 amination, and the most delicate anatomical operations, can 

 only show in the epidermis, one homogeneous layer, whose 

 adhering surface becomes insensibly confounded with the mu- 

 cous body, and which is deprived of cellular tissue, of vessels, 

 and of nerves. 



306. The thickness of the epidermis is but trifling, being 

 scarcely equal to the fifth or sixth part of that of the skin. It 

 is thicker in the palm of the hand, and the sole of the foot, than 

 any where else. In these places, particularly in mechanics, 

 or in persons who walk much, it appears to be formed of seve- 

 ral layers. M. Heusinger,* considers this part as a variety of 

 the horny tissue, and has described it under the name of the 

 callous tissue. The epidermis is not so elastic as the corium, 

 is very flexible and easily torn. It is transparent, and of a light 

 grayish colour. In the coloured races it partakes of the colour 

 of the skin, but it is not so deep as the corpus mucosum. The 

 transparency of the epidermis is not every where the same; 

 if we look at it against the light, we perceive points more 

 transparent than others, previously taken for pores. 



307. It is known that Leuwenhoeck thought he had per- 

 ceived them, and that he has figured them. Many have ad- 

 mitted them from this, or from physiological considerations. 

 But neither the observations of M. de Humboldt, made with 

 magnifying instruments greatly superior to those of Leuwen- 

 hoeck, nor those of Seiler, made upon the epidermis detached 

 by a razor, from the body of an animal while sweating, nor 

 my own, made by charging a piece of epidermis with a column 

 of mercury of about the weight of one atmosphere, have been 

 able to discover these pores. Again, observation teaches us 



* System der Mstobgia, von Heusinger Eisenach, 1822, 4to, 



