For our purpose, however, it will be sufficient to say that life began in the great bodies of water which were accumulating on the globe, and which owing to the washing down by rain and rivers and stream and wave action of land materials were becoming "saltier," or more highly charged with mineral salts of various kinds. The early forms of life were of the nature of jelly-fish, or simple organisms which were permeated by the fluid in which they dwelt. The sea was then warmer than it is now, and there are reasons for believing that it was something above 100° F., perhaps higher--perhaps rather hotter than we should now care to bathe in. It was also at the beginning an ocean which was much less salt and had much less lime in it than now. Its water was a good deal "softer." It was, however, becoming much more hard, more like the Dead Sea, which, as everybody knows, is a body of water so charged with mineral salts and accumulations that a bather cannot sink in it, and will emerge from his bath encrusted with salty deposits. As the early ocean became more and more saturated (with lime and carbonates, etc.), the more vigorous of the living forms in the water began to resist the change in various ways. They tried to meet it, or to alter themselves so as not to be incommoded by it. This is a very familiar occurrence in natural life and evolution. Perhaps the commonest example of it that we can select is the formation of corns on the human feet and hands. A corn, properly considered, is the defence raised by the skin against unusual or discommoding pressure or friction. When a boot is too tight, or when a plough handle or a cricket bat or a golf club is continually clasped tightly, a "callosity" or horn-like defence is formed. In some cases a blister is antecedent to the corn; and we may regard this not only as showing the need for the hardening of the skin, but as being a stage preliminary to it. There are many other instances. Hair is formed as a protection to the body, and owing to nature's economies is not usually formed when clothing takes its place or heat renders it unnecessary. If the heat is too great, or the light beating on the unprotected skin is too strong, then another form of protection takes the place of hair. Why is it that races living near the Equator wear "the burnished livery of the burning sun," and show black or brown pigmentation of the skin? It is because this pigmentation arrests the penetration of the rays of the sun more effectively than a garment. Lately Dr. Sambon has pointed out that the white linen clothes which Europeans generally wear in the tropics, though they look cool, are not sufficient screens against the rays of light and heat, and has suggested that white men's clothes, to be properly protective against the sun, ought to be woven of threads of two colours, so that the garments should be white outside and black inside. Apply these principles to animals in