42 



are supposed to be formed originally in every case within the vege- 

 table organism. Vegetable albumen, (the gluten of the seeds of our 

 cultivated cereals), and the vegetable casein, (the legumen of the 

 seeds of the Leguminosae) are some of their most important repre- 

 sentatives. Plants are therefore looted upon as the natural 

 resoiurcc from vv'hich the animal kingdom, directly or indirectly, 

 draws its requisite supply of nitrogenous matter for the formation 

 of blood and its subsequent deposition of animal tissues, bones, 

 muscles and fat. As a general rule, it must be conceded that they 

 are of j^articular importance, as far as a successful nutrition is con- 

 cerned, in their soluble modification, for in that condition they are 

 more apt to be directly convertible without particular exertion of 

 the apparatus of digestion. 



Fifth : Certain mineral substances, the phosphates, chlorides, 

 sulphates and carbonates qf both alkalies and alkaline earchs, 

 besides the oxides of ii-on and traces of manganese, silica and fluor- 

 ine are essential to the general promotion of animal life. They are 

 supplied by the mineral constituents of our articles of food. Fore- 

 most among these mineral constituents are the phosphates of lime, 

 soda, potassa and magnesia, the chlorides of sodium and potassium, 

 the sulphates of soda and j)otassa, and the oxide of iron, besides 

 smaller portions of carbonate of lime, fluoride of calcium, and siHcic 

 acid. 



These observations are based upon numerous comparative anaty- 

 ses of the principle constituents of the animal system, and of the 

 various kinds of food in use. The particular efliciency of our most 

 important articles of food have been besides — as is in this case of 

 controlling importance — repeatedly tested by practical experiments 

 under varying, yet well defined circumstances, for the purj)Ose of 

 securing a rehable basis in regard to the decision of the important 

 question : In what actual relation do the different constituents of 

 our various articles of food stand to the several functions, and the 

 normal workings of the animal system in general ? For many years 

 past, physiologists and chemists have advanced the following gen- 

 eral conclusions, which in their essential points are recognized 

 to-day. 



First There exists an actual connection between the nitrogenous 

 portion of our food and the formation of the animal tissues and the 

 amount of muscular power which we are able to exert. 



Second. There is a certain relation between the amount of non- 



