188 GENERAL ANATOMY. 



from without, all the foreign substances that enter into the 

 body to become portions of it, and from within outwardly, all 

 those which after having been parts of it, become foreign to it; 

 these substances and all others which are in contact with the 

 tegument, determine impressions on it; thus this membrane is 

 an organ of defence or protection of more or less efficacy, 

 against the action of external bodies ; it is the organ of external 

 absorptions and secretions, i. e. of those, the matter of which is 

 taken from, or deposited without ; it is the organ of all external 

 sensations, and of the feeling of want and appetite; and, finally, 

 through its appendages, it is sometimes an organ of offence or 

 aggression. But the functions of this membrane vary in the 

 different regions, according to the nature of its texture ; thus 

 the mucous membrane is better fitted for absorption and secre- 

 tion than the skin, while the latter is more adapted to receive 

 sensations and defend the body than the former. Some parts are 

 specially fitted for sensation, and even for this or that sensa- 

 tion, others for absorption, some for excretion, others for 

 generation, respiration, &c. 



255. The immense extent of the tegumentary membrane, 

 the number and importance of the functions of which it is the 

 seat and instrument, render its consideration a matter of much 

 importance, both in health and disease. Between the two 

 principal parts of which it is composed, there exists the most in- 

 timate relation, which in certain respects, was perceived by the 

 most ancient observers,* who knew that the abundance of the 

 mucous secretion is generally in an inverse ratio to that of the 

 cutaneous secretion. Observation has taught us that a healthy 

 state of the skin coincides with a similar condition of the mu- 

 cous membrane, and that, for instance, those persons whose 

 skins are very white, and of a fine delicate texture, are very 

 liable to diseases of the skin and mucous membrane, and 

 particularly to discharges from these two membranes. It 

 has also taught us that every part of the skin sympathizes with 

 the whole mucous membrane, and with this or that part of it 

 especially. There also exists an equally intimate relation be- 



XS/AM; VUMSTM. innOKPATOT2, TUV V/cT^c. B/3-X. f. 



