Page:Tropical Diseases.djvu/447

XXIV] exercise, excessive fatigue, want of sleep, constipation, are also to be avoided.

Clothing ought to be light and loose fitting, the under-garment being of thin woollen material. In going out in the sun the head must be protected by a wide -brimmed, well-ventilated pith hat shielding the temples and neck as well as the top of the head. An actinic theory of sun-traumatism, advocated many years ago by Maude and Duncan, and more recently by Sambon,* indicates the necessity for a radical change in the colour of the dress materials now in vogue among Europeans in the tropics. The natives of warm climates invariably have dark skins a natural provision of protection against the actinic rays of the solar spectrum. Exposure to the sun tans the European; a natural protective reaction. Therefore the European in the tropics, conformably to this hint from Nature, should invariably wear non-actinic colours a red or yellow shirt, or a fabric (solaro) into which these colours enter, and such as is now manufactured. The sun-hat should be similarly guarded. Experience has shown the comfort and value of such an arrangement. A pad of cotton sewn into the back of the coat in such a way as to protect the spine is a wise measure, and one adopted by experienced sportsmen in India. Puntone, who has shown by an ingenious experiment that the human cranium is diathermal to the yellow-red and ultra-violet rays but absorbs the red and green-blue rays, recommends green clothing covered with white material to protect important parts, more especially head, neck, and spine. The phenomena connected with the Rontgen rays suggest the possibility that there may be solar rays other than the ordinary heat and actinic rays which, although they may be able to pass through organic materials, can nevertheless be arrested by metals. If this be true for the sun as well as for the Rontgen rays, a useful addition to the sun-hat would be a thin plate of some light metal placed between the layers of pith constituting the basis of the ordinary solar topee. A sheet of tinfoil or other