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MR. MARTINEAU ON EVOLUTION.
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who come into Germany to work upon the railways always eat cheese with their staple food, maize. Other populations derive all their nutriment from 800 parts of bread and 100 of meat, besides potatoes and herrings. All these facts are in full accord with the experiment made on the dog, which lost weight on 800 parts of bread, or on the same with extract of meat, and finally died in convulsions.

On this subject we have the valuable researches of William Stark, dating from 1789. He tried experiments upon himself as to the relative value of different kinds of food. For 42 consecutive days he lived on 556 to 849 parts of bread and 900 to 1,800 water per day. Meanwhile he lost 17 lbs. weight. Then he took 736 to 962 of bread, 113 to 226 sugar and 900 to 1,300 water, and in 28 days lost 3 lbs. But he gained with 849 bread, 1,800 milk and 1,300 water. Hence it will be seen that prison-fare of bread-and-water is justly to be regarded as a punishment. In fact, the sentence condemning a man to live four weeks on such fare is in Danish law equivalent to sentence of death, and in Denmark no case has ever occurred of a culprit surviving his punishment.

Of course, Prof. Voit is far from condemning the use of vegetable substances for food; but he insists upon it that they must be combined with proper nutritive elements in assimilable form, in order to keep the body vigorous. These vegetable substances are deficient in albumen, and nothing can supply it better than flesh-meat. It is also advisable to substitute, for a part of the mass of starchy material, animal or vegetable fat. It is not denied but that one may sustain life on purely vegetable fare. The only conclusion the author insists upon in this first portion of his essay is, that the alimentation of man is always best secured, as regards azotic and fatty food, when the latter is got from animal matter, and oftentimes the elements in question cannot be derived from any other source. Chemistry alone will not account for this disparity. The principles of which we speak do not differ from one another chemically in their origin. It is only physiological experimentation, with the living being as the reactive agent, that can show these differing properties, as we have seen. This is a point of great importance. The question of nutritive salts, which we are next to consider, is no less important.—Revue Scientifique.

MR. MARTINEAU ON EVOLUTION.

By HERBERT SPENCER.

THE propriety of dealing with the leading criticisms that have been made on the general doctrine set forth in "First Principles"—more especially criticisms on the metaphysical aspects of that doctrine—has been from time to time pressed upon me. Having recently been led to