212 GENERAL ANATOMY. 



Those who admit of only two membranes in the skin, consi- 

 der it as the deep part of the epidermis. This mucous body, of 

 the nature of which it is difficult to form an exact idea, appears 

 to consist of a plastic liquid or a semi-organized cellular tissue. 

 Neither the blood, nor injections show any vessels in it; 

 liquids penetrate into it, however, but they seem to be im- 

 bibed by it, or to be contained in peculiar interstices. Nerves 

 are unknown in it, and it is by a pure allegation that Mr. Gall 

 assimilates it to the grayish substance of the brain. This 

 membrane forms a humid varnish which covers the papillary 

 and vascular surface of the dermis. Substances which enter 

 into, or depart from the economy by the skin, traverse it, it 

 is the seat of colour, and that of the horny, scaly, &c. produc- 

 tions, that exist naturally in the skin of animals, and in some 

 part of that of man, as well as of those that are accidentally 

 developed there. This membrane, which is so thin, and whose 

 existence has even appeared dubious, seems, in some animals, 

 and even in man, at least in some parts of the body, and in cer- 

 tain cases, to be found of several superincumbent layers. 



302. An anonymous author had already pointed out this 

 arrangement. Cruikshank observed it in a negro dead of 

 small-pox; Bay ham on the injected skin of a white man, in 

 another case of disease ; Gautier, by various processes, has de- 

 monstrated it on the skin of the negro, and M. Dutrochet on 

 the skin of animals. This is a sufficient number of observa- 

 tions, to demand an examination before we reject them: 1st, on 

 the papillary surface of the dermis, there is a very thin, co- 

 lourless, transparent layer, particularly distinguishable under 

 the scales and the coloured horns of animals, in the negro and 

 even in the white man, but under the nails only; 2d, a co- 

 loured layer very distinct in negroes, in whites marked with 

 coloured ephelides, and much less so where the skin is white; 

 it is often united to the following; 3d, a superficial colourless 

 layer, more or less soft or encrusted with a horny or calcarious 

 substance; it is distinct in several animals, slightly in the 

 negro, not at all in the white man, except in the nails, hairs 

 and accidental horny productions. This layer is directly co- 

 vered by the epidermis. 



