“It has been argued that fruits will not sustain life, because they do not contain sufficient nitrogen; this argument is founded upon a _theory_ which is demonstrably incorrect, and it is an ascertained _fact_ that fruits alone will support life and good bodily health.... By experiments on ourselves, on friends, and on natives of tropical regions, we find a comparatively small quantity of nitrogen necessary to sustain life; in fact, fruits, taken as a class, contain sufficient nitrogen to sustain human life.... Now fruits will sustain life, and all fruits contain carbon, hydrogen and oxygen, and most of them a small quantity of nitrogen; and if these fruits which will sustain life do not contain sufficient nitrogen, may not man, who breathes and is in contact with an atmosphere (four-fifths of which is nitrogen), by means of his lungs, the surface of which is supposed to be more than twenty times that of the whole body, _absorb the necessary nitrogen directly from the atmosphere_? From careful observation of the diet of natives in tropical regions, and from direct experiments in England, we may state that this is positively the case. This is often observed in the herbivora: their natural food contains little nitrogen, still it is found in their flesh in about the same ratio as in the carnivora. Further, the carnivora live on food rich in nitrogen—yet one is as well nourished as the other.... Man may live entirely upon fruits, in better health than the majority of mankind now enjoy. Good, sound, ripe fruits are never a cause of disease; but the vegetable acids, as we have before stated, lower the temperature of the body, decrease the process of combustion and oxidation—therefore the waste of the system—less sleep is required, activity is increased, fatigue or thirst hardly experienced: still the body is well nourished, and as a comparatively small quantity of earthy salts are taken into the system, the cause of ‘old age’ is in some degree removed, the effect is delayed, and life is prolonged to a period far beyond our ‘three score years and ten.’”[17] [17] “On one occasion, when living for five days entirely upon oranges, our temperature was lessened, still we felt a pleasant glow throughout the system; but to other individuals we felt cold; animal heat is therefore only _relative_. We further found that only three or four hours sleep was required in the twenty-four hours.” The consensus of modern opinion, however, seems to be against any such supposition. Chittenden, for example, writes:[18] [18] “Nutrition of Man,” p. 4. “Man lives in an atmosphere of oxygen and nitrogen. He can and does absorb and utilise the free oxygen of the air he breathes; indeed, it is absolutely essential for his existence, but free nitrogen likewise drawn into the lungs at each inspiration is of no avail for the needs of the body.”