If sunlight is so necessary to the perpetuation of life, and the production of normal development, it is equally necessary to the preservation of health and the prevention of "disease." if it is as necessary to life and health as are food and air, the body must inevitably be weakened and "diseased" in its absence. It fills an important need in the organism and its place cannot be filled by anything else. The highest degree of health cannot be attained and maintained without it.

It is essential to the restoration of health and hastens recovery in all forms of illness. I agree with Saleeby, who declares: "Every Sanitarium which is not essentially a solarium must today be called a tragic farce."

Etiolated plants are structurally weaker, possess less resistance to weather changes and to "disease" influences. They are unable to fructify and often unable to put forth leaves. "Etiolated" animals are the same. Their bones are more delicate, tissues less firm and resistant; they are short-lived, subject to "disease" and possess less resistance to weather changes. Plants grown in the dark lack color, and are unable to flower and fructify. Some of them, like the potato, are unable to put forth leaves. They are of very poor quality, breaking easily, and short-lived. Every cell and fiber in the plant and animal body is strengthened by the sun's rays. People who live in-doors out of the sun, are pale, weak and flabby. Every home should have a solarium.

Sunlight dominates the chemistry of the blood. People who do not get sunlight do not have the same richness and redness of blood as do those who secure plenty of sunlight. It is not merely that their skins are etiolated (pale and white), but one may appropriately say that their blood and inner tissues are also pale. There is not a tissue nor a function in the body that is not benefited by regular and judicious sun-bathing. Many experiments both in this country and England have shown, to use Saleeby's words, that "without any amelioration of a thoroughly vicious and defective diet, the amount of phosphorus in the blood will be doubled after a week or two of daily exposure, lasting a few minutes only, to sunlight. Some chemical process is thus begun, some ferment, or internal secretion, or 'hormone,' constructed which enables the body to take and keep and use, from the diet, what it would otherwise have to go without. And the children at the school in the sun, most inexpensively and simply fed without medicine or cod-liver oil, flourish and grow strong and straight, and remain so, doubtless because these mysterious and as yet unexamined vital processes are set going in their bodies by the prime source of all life and health."

Quinke and Behring have shown that the oxygen consumption of living cells, is vastly greater in light than in darkness. Light, by increasing the chlorophyll in plants, and hemoglobin in animals, both of these being oxygen carriers, exerts an enormous influence on the metabolic processes of oxidation, reduction and synthesis.

Sunlight greatly increases the body's consumption of oxygen. Through added numbers of red cells and increase in their hemoglobin, the oxygen carrying power of the blood is increased. Indeed, sunlight benefits the ailing human body in the same manner that it influences impoverished plant life--in both cases it increases the oxygen-carrying matter--hemoglobin or chlorophyll.

Heitel found that the double spectrum line of oxygen in the coloring matter of the blood is diminished by the action of light, to the single band of reduced hemoglobin. Light acts on the one hand to disrupt the oxygen molecule from its loose connection with the hemoglobin, and on the other hand, to facilitate its combination with oxidizable food substances. Behring and Meyer pointed out that this process consists in activating certain oxidation ferments present in the blood (peroxidosis).

A few minutes of exposure daily to the sunlight will double the quantity of phosphorus in a baby's blood in a fortnight. The circulation of the blood itself is improved while blood-pressure is lessened. The power of the blood to build and repair tissue is increased, and its coagulating power greatly improved. Sun baths are indispensable to hemopheliacs or "bleeders."

Dr. James C. Jackson says that "a man who lives out in sunlight will grow thin in flesh but full in nerve. His muscles will diminish, but as they diminish his nerves become increased in size and strengthened, and their action on the muscles is such as decidedly to strengthen these; so that when one comes to look at him and judge of his strength by his apparent bulk, if he does not understand and fully appreciate the effect of living largely in the sunlight, he will greatly misjudge his muscular capacities."

In view of our greater knowledge of the influence of the sun upon the muscles, we are sure that what Dr. Jackson mistook for a decrease in muscular size coincident with an increase in strength and endurance, was, in reality, a loss of the fat in the muscles. It is not likely that the nerves increased much, if any, in size, but it is certain that they improved in quality and condition and increased their control over the muscles.

Describing tubercular patients, which he saw at Rollier's place, who received no exercise, and whose bodies were warm, though nude, while the air was quite cool, Saleeby says: "This would seem to be a puzzle, for these patients have, in many instances, never moved a muscle--practically speaking--for months; they have not even had their muscles innervated (sic) by the farradic current; they have not been massaged. But always the muscles are firm and well developed under the warm skin. 'The sun is the best masseur,' said Dr. Rollier to me; and one realized that the stimulant light, playing upon the nude skin in the cool air, induces and maintains that condition of tone in the muscles which, indeed, moves no points but is yet a form of muscular activity essential for the production of bodily heat and for the proper posture of the bodily parts. Hence we understand how plaster of Paris is here as utterly unknown as the knife. The tone of the muscles, thanks to the nude skin and the reflex response to the light, is enough to keep the recovering young spine, for instance, in proper position, and to form what Rollier calls the 'corset musculaire.' One sees very little fat on any of the patients. Their condition is more like that of the trained athlete, and one's ideas as to the importance of fat in tuberculosis go by the board."