RELATIONS OF THE MOUTH. C85 



The digestive function, for instance, comprises a series 

 of sub-divisions or functions, constituting so many links or 

 stages, each one of which is essentially related with, and 

 dependent upon every other and the whole; and the whole 

 upon each, for the completion and perfection of this won- 

 derful and complicated process, styled digestion. 



The function of digestion begins in the mouth by sub- 

 jecting the crude material of nutrition to the several opera- 

 tions of mastication, insalivation, and deglutition, and the 

 aliment having arrived in the stomach, the function is 

 there continued, by converting this aliment into chyme, 

 whence it is conducted into the small intestine, and there 

 undergoes its final change, by being formed into chyle, and 

 thus completing the whole process of digestion. 



But the relation of the mouth, in this series of physio- 

 logical actions, does not stop here ; for we follow the chyle 

 through the great trunk of the absorbent system, into the 

 left subclavian vein, thence through the heart to the lungs, 

 where, with the venous blood, and by atmospherical agency, 

 it undergoes its final and most perfect change ; in other 

 words, is formed into arterial Wood, the only and proper 

 pabulum by which the mouth, as well as the whole body 

 with all its organs, is built up and sustained. 



To accomplish this result, we now trace this fluid blood 

 from the lungs into the heart and arteries, by which latter 

 it is distributed over the whole body, and consequently 

 brought back to supply the mouth, the point where began 

 the first change in this most beautiful series of operations 

 so essential to the formation of this vital fluid. 



These several relations, anatomical and physiological, 

 thus briefly sketched, which the mouth has with the vari- 

 ous organs, shows an intimacy of connection, not only close, 

 but inseparable. Hence the dental student will perceive 

 the absolute necessity of not confining his anatomical 

 studies solely to the mouth, but of examining studiously 

 every organ and portion of the body with which the mouth 

 has any relation, as necessary steps to becoming completely 

 master of his profession. 



