50 ORGANS OF DIGESTION. 



each by the admission of anatomists, the follicles described 

 commonly by them, are of this description, and are not compa- 

 rable in number to the follicles found in the venous meshes. 

 The highest estimate of the number of the former, as made by 

 M. Lelut, fixes them at about forty-two thousand.* In consult- 

 ing many of the distinguished modern authorities on this sub- 

 ject, there seems to be scarcely any thing in the anatomy of the 

 intestinal canal which is presented in a more indefinite way; 

 especially in regard to the small intestines, than the difference 

 between the follicles, properly speaking, and the glands; and 

 none of them, so far as I know, have undertaken to approximate 

 the entire number of the follicles and to point out how each one 

 is the centre of a venous anastomosis, is formed by it, and 

 always exhibits itself in a collapsed state when the vein is not 

 turgid.f 



SECT. IV. OF THE GENERAL ANATOMY OF THE MUCOUS MEMBRANES. 



The extent of the mucous coat of the alimentary canal, and 

 the important and varied sympathies which it has with most 

 other parts of the body, render useful some remarks on mem- 

 branes of this kind generally. Mucous Membranes are so called 

 from the nature of the secretion which they furnish : and the 

 term having been first applied to the lining coat of the nose, a 

 similitude of character has caused its extension to that of other 

 organs. The celebrated Bichat, the founder of the science of 

 general anatomy, was the first to adopt fully, and to perceive 

 the value of this classification; since which it has been almost 

 universally received by anatomists. 



As the skin forms an external covering to the body, so mu- 

 cous membrane lines the internal surface of the hollow vicera. 

 When it is recollected that this membrane forms fan internal 

 tegument to the whole alimentary canal, from the mouth to the 

 anus; to all the urinary and genital apparatus; to the whole 

 respiratory system, from the nose down the trachea and through- 

 out the lungs; it will be admitted that its extension exceeds 

 much that of the skin. 



* Bouillaud, Traite du Cholera, p. 256. 



t The anatomy of the Castro-intestinal mucous membrane has elicited several 

 good papers in Europe since 1835, inclusive. They are rather confirmatory of 

 preceding observaitona than distinguished by novelties, and the venous anasto- 

 mosis does not seem to be understood or appreciated. 



