vantages of four or five degrees of coolness gained by closed windows and Venetians, for the difference is no more. But breathing impure air is not the only inconvenience of closed doors and Venetians; the prevading darkness is equally as prejudicial to health: the parallel between animal and vegetable Use is too generally true not to hold good in the circumstance of light. That darkness is injurious to the healthy growth of vegetables is well ascertained; plants that live in darkness remain pale, flaccid, and feeble, and those accustomed to sunshine, if removed to a dark situation, rapidly lose their health and droop and die. The bills of mortality clearly show that the inhabitants of dark lanes and alleys are more unhealthy than those in well lighted streets, and nice investigations have proved, that the tenants of the shady sides of streets are less healthy than those of the sunny—moreover, practical experiments have demonstrated that tadpoles do not become mature frogs if kept in the dark.
The indigo planters are good examples of the truth of this theory. They are the most healthy looking people in India, though exposed all day, at all seasons, to the sun; the injurious effects of heat being counterbalanced by fresh air, light and exercise. The contrast between such men at the end of a hot season and those shut up in close dark houses is very remarkable.
