[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