OBJECT OF DIGESTION. 209 



digestive organs, must first undergo a change, from being 

 subjected to the influence of the juices of these organs. This 

 is because the food, received into the mouth, traverses the 

 different parts of the digestive canal successively, and is sub- 

 jected in its course to various mechanical influences, espe- 

 cially that of the different fluids which serve to liquefy and 

 transform it. These modifications are not generally very 

 striking ; they appear to affect only the state of cohesion of 

 the substances ; insoluble elements being rendered soluble, 

 and coagulable elements incoagulable, etc., while the un- 

 changed parts are thrown off". 



No aliment is complete, unless it contains all the elements 

 of which the tissues of the body are composed. 



1. Beside their organic principles the animal and vegetable 

 matters which we consume contain various mineral products: 

 such are the alkaline or alkaline-earthy salts, sulphur, phos- 

 phorus, iron, all elements necessary to every cell of our 

 organs. Iron is administered to a chlorotic person as food, 

 because iron, which is one of the indispensable elements of the 

 economy, has been diminished in the blood. These mineral 

 substances alone, are incapable of supporting life ; and if 

 those which are borrowed from the organic kingdom are 

 found sufficient for this purpose, it is only because they con- 

 tain in themselves a certain proportion of mineral matters. 



The mineral salt that appears most indispensable to nour- 

 ishment is chloride of sodium. Daily experience proved 

 long ago that man cannot do without this salt, and the reli- 

 gious corporations which sought to subject themselves to the 

 severest privations, tried in vain to banish chloride of sodium 

 from their food. Physiological experiments on animals show 

 (Wundt, Rosenthal, Schultzen) that this salt is indispensable 

 to the system, and serious consequences have followed its 

 suppression. Physiological chemistry explains these facts by 

 showing that chloride of sodium enters into the composition 

 of nearly every part of the organism, and is especially indis- 

 pensable to the constitution of the blood serum and carti- 

 lages. It appears to assist in the process of the nutrition of 

 the tissues, and is indispensable to the formation of the bile, 

 pancreatic and gastric juices. Cattle-breeders are well 

 acquainted with the favorable influence produced on the 

 development of animals by administration of chloride of 

 sodium; without asserting tjiat mixture of this salt with the 

 food produces increase of growth and fat> we must admit 

 (Boussingault) that animals fed in this way have more 



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