OF THE TEGUMENTARY MEMBRANES IN GENERAL. 1ST 



250. The surface of the dermis is covered with a layer 

 more or less distinct, according to the part of the tegument, 

 and which is called the mucous or reticulated body; it is cel- 

 lular tissue, in a semi liquid, or imperfectly organized state, 

 in which the most minute divisions of the white vessels arise 

 or terminate; this layer, otherwise very compound, is the seat 

 of the colour, and that of the horny incrustations which cover 

 the teguments in some places. This layer is less distinct in 

 the mucous membranes than in the skin* 



251. Finally, the epidermis is the last essential part of 

 the tegumentary membranes, that which forms their free sur- 

 face; it is an albuminous layer excreted on the surface of the 

 mucous body. In many parts of the mucous membranes, the 

 epidermis is not distinct and seems to be substituted by mucus. 

 Independently of this, and as regards the chemical nature of 

 the matter, there is much resemblance between the epidermis 

 and mucus. 



252. Several parts of the tegumentary membranes, are 

 provided with salient appendages on their free surface: those 

 are, the nails and hairs for the skin; and the teeth, for the 

 mucous membrane. 



253. By decoction, the teguments are resolved almost en- 

 tirely into gelatine. The very different colours of the tegu- 

 ments depend partly upon that of the blood and partly upon 

 a colouring matter secreted from it, in the mucous body. Their 

 very variable density, is nearly intermediate between that of 

 the cellular, ligamentous, and elastic tissues. Their elasticity 

 is tolerably well marked. They possess, also, a very great, 

 but slow extensibility and retractability, Their formative 

 power is highly developed. Although their irritability is 

 much less evident than that of the muscles, they possess a 

 large share of it. They are the essential organ of sensibi- 

 lity. 



254. The organic action or function of the tegumentary 

 membrane is very important, very complex and different in 

 the different parts of that membrane. As a tegument or en- 

 velope of the mass of the body, internal as well as external, 

 it constitutes a barrier through which must pass inwardly 



