70 OF THE NERVES AND MUCOUS FOLLICLES. 



which they communicate with the cavity of the intestine, or 

 that they are so exceedingly minute, that no one has yet been 

 able to discover them with the microscope. The origin of the 

 lacteals in the villi, is, in all probability, the same as that of 

 absorbents in other parts of the body, by a net-work of 

 extreme minuteness.* 



Fig. 139.f Fig. 139, is a representation of the 



origin of the absorbents from the mu- 

 cous membrane of the stomach, in the 

 form of a net- work as they appeared 

 to Breschet. 



The presence of such intestinal villi, 

 as are found in man and the superior 

 animals, is not indispensible to chylous 

 absorption, for in a large number of 

 animals, the internal surface of the small intestines is destitute 

 of villi.J 



Of the Nerves. 



The nerves of these membranes, are derived in many parts, 

 as the intestines, biliary ducts, etc., mainly from the sympa- 

 thetic nervous system ; hence such parts are necessarily devoid 

 of animal sensibility. In the stomach, upper part of the 

 duodenum, oesophagus, mouth, lungs, and rectum, the mucous 

 membrane receives branches likewise from the cerebro-spinal 

 system of nerves. 



Of the Blennogenous or Muciferous Glands. 



These exist in great numbers in all mucous membranes, and 

 are the source of the mucous substance, which covers the surface 

 of the membrane. 



* This is a doctrine long since advocated by Hewson. p. 

 f ff, A layer of superficial absorbents, b, A layer more deep seated. 

 $ Gerber has suggested as the result of some of his microscopical operations, 

 that the central cell or vesicle in the columns of the cylinder epithelium, which 

 covers the surface of the villi as well as other parts of the membrane, commu- 

 nicates below with the lacteal absorbents, and assists in chylous absorption. 

 But this is an opinion, which requires further confirmation. P. 



