On leaving our great Chemist, I went to a Physiologist, whose opinion has no less weight with me, and to him I put the same question. His reply was very long and very beautiful. In substance it ran thus: "We know in reality no more about the composition of water than we know about that of blood. What we best know and can most safely affirm about the _mucus_ of sea water, is that it is at once an Alpha and an Omega, a beginning and an end. Is it the result of the numberless deaths which furnish forth materials for new lives? No doubt, that is the general law; but in the case of the sea, that world of rapid absorption, the majority of the creatures there are absorbed while in full life; they do not slowly linger on towards death, as we on land do. The sea is a very pure element; war and death purvey to it. But life, without arriving at its final dissolution, is incessantly approaching it, exuding and exhaling all that is superfluous. With us, the animals of the earth, the epidermis, through its millions of pores, wastes the body at every instant; we suffer, as it were, a partial death at every breath we draw. Now this partial death, this vast exudation, in the case of the marine world, fills that vast world of waters with a gelatinous wealth of which the young world has the instant benefit. It finds in suspension the oily superabundance of this common exudation, the still living atoms and liquids which have not had time to die. All this does not fall back into the inorganic, but enters quickly into new organisms. Of all the theories on the subject, this seems the most reasonable; rejecting this theory, we plunge into a sea of extreme difficulties." These ideas of the most enlightened and earnest thinkers of the present day, are not irreconcilable with those which, nearly thirty years ago were promulgated by Geoffrey Saint Hilaire, upon that general _mucus_ in which nature seems to find all life. He calls it "the _animalisible_ substance, the raw material of organic bodies. Not a creature, whether animal or vegetable, but both absorbs and produces it from the earliest to the latest breath; indeed, the weaker the creature, the more abundant that is." This remark suggests a broad and bright light upon the life of the seas. Their tenants seem, for the most part, foetuses in the gelatinous stage, which absorb and produce the mucous substance, permeate and saturate with it all the waters, and give to them the fecund and nourishing powers of a vast womb, in whose depths an infinite succession of generations, perpetually float, as in warm milk.