Page:Substance of the Work Entitled Fruits and Farinacea The Proper Food of Man.djvu/39

 gluten appear to be fundamentally the same, and are the substance of the human muscles. The other elements of food, which support respiration and supply animal heat [as also vital force], are divided by Dr. Prout into two groups— the saccharine, comprehending sugar, starch, and gum; and the oleaginous, in which he includes oils, fat, and spirits. Passing over some few points of controversy, we find no question that this second element of food must supply carbon and hydrogen, which are essential for vital force and animal heat, as also to save the lungs from destruction by the oxygen of the air. Yet I shall presently assign reasons for doubting whether this is the sole use of the saccharine element.

2. We next inquire whether vegetables will furnish to man these necessary elements of food. Some years ago, when it was supposed that vegetable substance was destitute of "azote," or "nitrogen," it was argued that,, for the renewal of our muscular tissues flesh meat was needed. But as the flesh of sheep and oxen is acknowledged to contain as much nitrogen as the flesh of man, I ask, whence do they derive it? They do not eat flesh. Then man, without eating flesh, may get it as they do, since his anatomy is like theirs; whether they get it from their vegetable food, or from the nitrogen in the atmosphere. This is a thorough and sufiicient reply. Nevertheless, I find it instructive to go minutely into the question of the supply of nitrogen.

The carnivora never masticate their food, but the herbivora and man do; and in the process the food becomes mixed with the saliva, which (according to Liebig) encloses air in the shape of froth. "This air," says he, " by means of the sallva, reaches the stomach with the food, where its oxygen enters into combination; while its nitrogen is given out through the skin and lungs, without being applied to any use in the animal economy." The last words of Liebig seem to me supported by no evidence; nor can I believe that nature would allow nitrogen to be incessantly passing through the various tissues of the body without answering some useful purpose. Is it not possible that additional nitrogen may be thus supplied to the system when the food does not contain enough? To this Dr. Prout seems to assent when he remarks: "This involution of azote may be considered as one of the great objects of mastication and insalivation, which are