[13] “There is no profession, there is no calling or occupation in which men can be engaged, there is no position in life, no state in which a man can be placed, in which a fairly developed frame will not be valuable to him; there are many of these, even the most purely and highly intellectual, in which it is essential to success—essential simply as a means, material, but none the less imperative, to enable the mind to do its work. Year by year, almost day by day, we see men (and women) falter and fail in the midst of their labors; ... and all for want of a little bodily stamina—a little bodily power and bodily capacity for the endurance of fatigue, or protracted unrest, or anxiety, or grief.”—Maclaren’s Physical Education.
[14] “One half the struggle of physical training has been won when a boy can be induced to take a genuine interest in his bodily condition,—to want to remedy its defects, and to pride himself on the purity of his skin, the firmness of his muscles, and the uprightness of his figure. Whether the young man chooses afterwards to use the gymnasium, to run, to row, to play ball, or to saw wood, for the purpose of improving his physical condition, matters little, provided he accomplishes that object.”—Dr. D. A. Sargent, Director of the Hemenway Gymnasium at Harvard University.
[15] “It is health rather than strength that is the great requirement of modern men at modern occupations; it is not the power to travel great distances, carry great burdens, lift great weights, or overcome great material obstructions; it is simply that condition of body, and that amount of vital capacity, which shall enable each man in his place to pursue his calling, and work on in his working life, with the greatest amount of comfort to himself and usefulness to his fellowmen.”—Maclaren’s Physical Education.
[16] To this classification may be added what are called albuminoids, a group of bodies resembling proteids, but having in some respects a different nutritive value. Gelatine, such as is found in soups or table gelatine is a familiar example of the albuminoids. They are not found to any important extent in our raw foods, and do not therefore usually appear in the analyses of the composition of foods. The albuminoids closely resemble the proteids, but cannot be used like them to build up protoplasm.
[17] The amount of water in various tissues of the body is given by the following table in parts of 1000:
| Solids. | Liquids. | ||
|---|---|---|---|
| Enamel, | 2 | Blood, | 791 |
| Dentine, | 100 | Bile, | 864 |
| Bone, | 486 | Blood plasma, | 901 |
| Fat, | 299 | Chyle, | 928 |
| Cartilage, | 550 | Lymph, | 958 |
| Liver, | 693 | Serum, | 959 |
| Skin, | 720 | Gastric juice, | 973 |
| Brain, | 750 | Tears, | 982 |
| Muscle, | 757 | Saliva, | 995 |
| Spleen, | 758 | Sweat, | 995 |
| Kidney, | 827 | ||
| Vitreous humor, | 987 | ||
[18] The work of some kinds of moulds may be apparent to the eye, as in the growths that form on old leather and stale bread and cheese. That of others goes on unseen, as when acids are formed in stewed fruits. Concerning the work of the different kinds of moulds. Troussart says: “Mucor mucedo devours our preserves; Ascophora mucedo turns our bread mouldy; Molinia is nourished at the expense of our fruits; Mucor herbarium destroys the herbarium of the botanist; and Choetonium chartatum develops itself on paper, on the insides of books and on their bindings, when they come in contact with a damp wall.”—Troussart’s Microbes, Ferments, and Moulds.
[19] “The physiological wear of the organism is constantly being repaired by the blood; but in order to keep the great nutritive fluid from becoming impoverished, the matters which it is constantly losing must be supplied from some source out of the body, and this necessitates the ingestion of articles which are known as food.”—Flint’s Text-book of Human Physiology.
[20] Glands. Glands are organs of various shapes and sizes, whose special work it is to separate materials from the blood for further use in the body, the products being known as secretion and excretion. The means by which secretion and excretion are effected are, however, identical. The essential parts of a gland consist of a basement membrane, on one side of which are found actively growing cells, on the other is the blood current, flowing in exceedingly thin-walled vessels known as the capillaries. The cells are able to select from the blood whatever material they require and which they elaborate into the particular secretion. In Fig. 47 is illustrated, diagrammatically, the structure of a few typical secreting glands. The continuous line represents the basement membrane. The dotted line represents the position of the cells on one side of the basement membrane. The irregular lines show the position of the blood-vessels.
[21] Tablets and other material for Fehling and additional tests for sugar can be purchased at a drug store. The practical details of these and other tests which assume some knowledge of chemistry, should be learned from some manual on the subject.