OF THE MUCOUS MEMBRANE. 199 



4. Sensations, more or less distinct or obscure, general or 

 special, and feelings of want, or of appetites. 



277. The mucosities or the mucous humours that are 

 found on the surface of the internal tegument, are for the 

 most part composed of mucus. Animal mucus* very ana- 

 logous to vegetable mucilage, but containing nitrogen in addi- 

 tion, is one of the immediate principles of animals. It is 

 found both internally, in the product of the mucous secretion, 

 and externally in the epidermis, hairs and horny parts, of 

 which it forms a considerable portion. In a pure and liquid 

 state, it is white, viscid, transparent, inodorous, and insipid; it 

 contains nine-tenths of its weight of water; it is insoluble in 

 alcohol, soluble in acids, not coagulable like albumen, and not 

 congelable like gelatine; it is precipitated^ by the acetate of 

 lead; in a dry state it is semi-transparent, fragile, insoluble 

 in water, soluble with difficulty in acids. 



M. Berzelius has proved the identity of the mucus of the 

 nose and trachea, and found it composed as follows: water, 

 933.9; mucous matter, 53.3; hydrochlorate of potash and 

 soda, 5.6; lactate of soda and animal matter, 3.0; soda, 0.9; 

 phosphate o soda, albumen and animal matter, 3.3. 



In the analysis of the other mucosities given by this savant, 

 and in those of Messrs. Fourcroy and Vauquelin, there are con- 

 siderable differences, some of which depend on the difference 

 of parts whence the mucosity was taken, and where it had 

 been mixed with various matters, and others on the difference 

 of the individuals affected with different diseases. In fact, 

 although mucus is always identical, mucosity is neither al- 

 ways nor everywhere the same; generally it coagulates milk. 



278. The functions of the mucous membrane are very 

 closely connected with those of the other parts. In a healthy 

 state, the nervous action, the circulation, the functions of the 

 skin, &c. have a manifest influence on the functions of the 

 mucous membrane, and vice versa. In a state of disease, the 

 mucous membrane produces very remarkable sympathetic 

 effects, and experiences also those produced by other parts. 



* See. Fourcroy and Vauquelin, Annahs du Mus. cThist. nat. vol. xii. 

 Bostock, Medico-Chir. Transact, vol. iv. Berzelius, ibid vol. iii. 

 27 



