The food of man can not be healthful and adequate unless it supplies the proper amount of the different nutritive ingredients, or "" nutrients.'1 Practical experience proves this, and experimental inquiry demonstrates it as well. Just what the functions of the different foods are-their ""nutritive value and cost""-has been discussed in Bulletin No. 142 of this series, and a knowledge of the facts there set forth is necessary to a clear understanding of the present bulletin.It is natural to divide foods into two classes-animal food and vegetable food. Not only is this division simple and convenient, as pointing out the two great sources of man's food, but the classification is a true one, for .the difference between animal and vegetable food ia very striking in appearance, composition, and value in the economy of life. It is true that many of the chemical compounds which enter into the composition of these two classes of food are either alike or quite similar; but in general tAbout the Publisher Forgotten Books is a publisher of historical writings, such as: Philosophy, Classics, Science, Religion, History, Folklore and Mythology.Forgotten Books' Classic Reprint Series utilizes the latest technology to regenerate facsimiles of historically important writings. Careful attention has been made to accurately preserve the original format of each page whilst digitally enhancing the difficult to read text. Read books online for free at www.forgottenbooks.org