GENERAL ANATOMY OF THE MUCOUS MEMBRANES. 55 



the lungs, rapidly communicating the particular smell of this 

 article to the urine. There are, moreover, cases recorded of 

 obstructed urethra, where the urine has been almost entirely 

 absorbed by the mucous coat of the bladder. ^ 



In regard to nerves, the mucous membranes are well fur- 

 nished with them. Bichat has remarked that wherever these 

 membranes are situated near the surface of the body and enjoy 

 common sensibility, they are almost wholly furnished from the 

 central portions of the nervous system, as the brain and spinal 

 marrow: this is exemplified in the conjunctiva, the pituitary 

 membrane, the palate, the glans penis, &c. On the contrary, 

 the sympathetic nerve furnishes the intestines, the bladder, and 

 the excretory tubes generally. 



Mucous Glands, as they are called, exist throughout the sys- 

 tem of mucous membranes, being situated either under them or 

 in their thicknesses. From them is derived the mucilaginous 

 fluid which lubricates so abundantly their interior surfaces, so 

 as to facilitate the passage of extraneous bodies, and, at the 

 same time, to protect the membrane from mechanical violence. 

 These glands are of various sizes, from that of the tonsils and 

 the muciparous glands on the lips, cheeks, and root of the tongue, 

 to the almost imperceptible crypta? of the bladder and urethra. 

 Their shape is either lenticular, rounded, or that of a pouch. 

 The two former have their parietes of a sensible thickness, but 

 the last are too thin to be distinguished from the mucous mem- 

 brane itself. For the most part, the excretory duct of these 

 glands is short and patulous, so as to lead directly into the sub- 

 stance of the gland. This is remarkably the case with the ton- 

 sils, which consist in a congeries of these follicles; and with the 

 glands on the root of the tongue. In some animals they are so 

 numerous as to form almost a distinct lamina to the intestines; 

 after the manner of the human subject, on the palate and pa- 

 rietes of the mouth. 



The Mucosity discharged from these glands is one of the 

 principles of animals, and, as is well known, exists also to a 

 great extent in some vegetables. When perfectly pure and 

 fluid, it is white, transparent, inodorous, and insipid. It is in- 

 soluble in alcohol, but soluble in acids. Water forms more 

 than nine-tenths of it, the remainder is mucus, properly speak- 

 ing, blended with some neutral salts of soda and potash. 



