DIGESTION OF FOOD. 



349 



terms osmosis and diffusion in connection with the functions 

 of the alimentary canal, and especially the intestinal tract, 

 as if this thin-walled but complicated organ, or rather collec- 



FiG. 286.— A. Villi of man, allowing blood-vessels and lacteals; B. Villus of sheep 

 (after Chauveau). 



tion of organs, were little more, so far as absorption is con- 

 cerned, than a moist membrane, leaving the process of the re- 

 moval of digested food products to be explained almost wholly 

 on physical principles. 



From such views we dissent. We believe they are opposed 

 to what we know of living tissue everywhere, and are not' sup- 

 ported by the special facts of digestion. When certain foreign 

 bodies (as purgatives) are introduced into the blood or the ali- 

 mentary canal, that diffusion takes place, according to physical 

 laws, may indicate the manner in which the intestine can act ; 

 but even admitting that under such circumstances physical 

 principles actually do explain the whole, which we do not grant, 

 it would by no means follow that such was the natural behav- 

 ior of this organ in the discharge of its ordinary functions. 



