Page:Popular Science Monthly Volume 66.djvu/456

452 whatever the age of the individual exposed; and no less against diseases not attributable to germs—and the more if we accept Metschnikoff's theory of the office of the leucocytes or white blood corpuscles, for these in both number and strength depend upon proper nourishment. 'In health' says Kirke, 'the proportion of white to red corpuscles, which, taking an average, is about 1 to 500 or 600, varies considerably, even in the course of the same day. The variations appear to depend chiefly on the amount and probably also on the kind of food taken, the number of leucocytes being very considerably increased by a meal, and diminished again on fasting. Also in young persons, during pregnancy, and after great loss of blood, there is a large proportion of colorless blood corpuscles, which probably shows that they are more rapidly formed under these circumstances. In old age, on the other hand, their proportion is diminished.'

No good observer will fail to recognize the coincidence of the condition which diminishes the proportion of leucocytes and the increased liability to disease—that of fasting; or note the no less remarkable coincidence, the diminution in the number of leucocytes and increasing infirmity of old age.

Foods are ordinarily divided into four classes: (1) Nitrogenous or albuminous substances; (2) fats or hydrocarbons; (3) carbohydrates, chiefly starchy substances and sugar; (4) mineral substances—water and salts.

The average daily amount of food required and of the different kinds, as comprehended in this classification, severally, varies considerably with individual conditions of age, size, exercise, circulation, activity of the eliminating organs, etc. The range in different male adults is from 34 to 46 ounces of so-called solid food, and from 70 to 90 ounces of water in some form, taken with and without solid food. For adult females, the average is from 3 to 5 ounces less. For children and youths, proportionally, more in the inverse ratio to age, 0.8 to 0.6 ounces for each pound weight of the body.

If individuals are undergoing great exertion they require more food, and, if they can obtain it, the needful increase is especially in the nitrogenous and fat foods.

Every structure in the body in which any form of energy is manifested (heat, mechanical motion, chemical or electric action, etc.) is nitrogenous. The nerves, the muscles, the gland-cells, the floating cells in the various liquids, the semen, and the ovarian cells, are all nitrogenous. Even the non-cellular liquids passing out into the alimentary canal at various points, which have so great an action in preparing the food in different ways, are not only nitrogenous, but the constancy of this implies the necessity of the nitrogen in order that these actions shall be performed; and the same constancy of the presence of nitrogen, where function is performed, is apparently traceable through the whole world. Surely such constancy proves necessity. (Parkes.)