Page:Popular Science Monthly Volume 41.djvu/107

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production, the one having a ratio of 1 to 5, and the other of 1 to 5·1, but there is a difference in potential energy in the two rations equivalent to over 2,411,000 kilogramme-metres of work, or one and a quarter horse-power in the day's rations.

In two other rations for milk-production with nutritive ratios of 1 to 5 and 1 to 5·1, the difference in potential energy would be represented by 3,112,000 kilogramme-metres, or 1·6 horse-power for the day's feed.

There are likewise rations with exactly the same nutritive ratio (1 to 5), prescribed for Jersey cows giving milk, in which the difference in potential energy is equivalent to 1,123,600 kilogramme-metres, or more than one half of a horse-power for the day's feed. There are also rations for horses, with nutritive ratios 1 to 6, and 1 to 6·4, which have a difference in energy of 2,834,000 kilogramme-metres, or the equivalent of over one and a quarter horse-power for the day.

It is unnecessary to cite further instances of the obvious fallacies in rations that have been formulated in accordance with a theory which ignores the significance of energy in animal nutrition. The facts already presented must be sufficient to show that the law of the conservation of energy should be recognized as an important factor in the nutrition and growth of both plants and animals, and that it should receive due attention in planning and conducting experiments for the promotion of agricultural science, and in interpreting their results. In the development of a rational system of farm economy the applications of this general law must have a dominant influence in determining the most profitable and consistent methods of practice.



EXERCISE, as well as pure air, helps us in our constant struggle against the poisons that we manufacture within ourselves. It does this by driving the blood charged with oxygen, by means of the pressure of the muscles called into play, more thoroughly through the tissue (Foster, page 219); and thus it would quicken the breaking down of dead tissue into its safe and final waste products (water, carbonic acid, and urea), and shorten the period during which the dead tissue was passing through various dangerous forms which it temporarily assumes. From this fact we may infer that the man of sedentary life, above all others, requires pure air.

In truth, pure air and exercise are equal forces acting in the