“Air and light are essential to the development of the higher forms of animal and vegetable life in full vigour and perfection. The lowest organisms--fungi and bacilli and bacteria whose office in nature appears to be to prey upon and hasten the decomposition of their superiors in the scale of life--love, like other evil things, darkness and close dwellings. Bright sunlight (the most potent and valuable of all light) and fresh air (by oxygen the portion of food used as fuel is burnt, and heat and all forms of energy evolved, and oxygen is required for the changing and removal of waste) are as inimical to them as they are beneficial to the more perfect forms above them. The action of light is known with less precision than that of oxygen. It appears, however, to be essential to the perfect formation of the red cells of the blood--its most vital constituents. Persons who are deprived of light grow pale and bloodless. Young women brought from the country as servants or shop girls, and kept in cellar kitchens or dark work-rooms, notoriously suffer in this way. Miners also are a pallid, anæmic class. The want of fresh air has something to do with the result no doubt; yet patients in a well-lighted hospital ward appear to recover more quickly, as a rule, than those in darker rooms equally well ventilated. [Compare the interesting statistics collected in St. Petersburg by Sir James Wylie.] Altogether common experience and observation confirm the conclusion which science has hardly yet formulated, that light has a powerful and favourable influence upon animal life. Human beings grow blanched just as plants do, for the want of it. And it is not a question of colour merely; vitality is seriously lowered also. This is largely felt in great towns shaded by fog and smoke-clouds. Some recent remarkable experiments have shown that the electric light exerts a favourable influence on vegetation, second only to sunlight. It is possible that it may in like manner foster animal life.” Dr. W. B. Cheadle in “The Book of Health.” * * * * * In addition to the experiments on vegetation, at Cornell University in America, and by Professor Siemens in England, recent experiments have shown the value of electric light in general, and of certain colour-rays in particular, in the treatment of various diseases such as gout and its sisters and cousins, nervousness, lupus, and so on. There are already several establishments in London where electric light cures are to be obtained. Dr. Forbes Winslow in his treatise on Light speaks even more emphatically than Dr. Cheadle does about the bad effects of the absence of light. He says:-- * * * * *