Whether or not it is possible for new varieties and species to be evolved is a question, therefore, which does not need to depend for reply wholly upon theory. It is known to have taken place; and the process by which the different varieties of domestic animals and plants have been evolved—domestic selection—is not different in principle from the process of natural selection, the chief operation by which life in general, both plant and animal, is assumed to have been evolved. 10. There are other reasons for a belief in organic evolution, but the last one I shall mention is the fact that the theory of organic evolution harmonises with the known tendencies of the universe as a whole. The organic kingdoms of the earth—animals and plants—are as truly parts of the terrestrial globe as the inorganic kingdom is; and as such they share in, and are actuated by, the same great tendency or instinct as that which actuates the whole. Nine-tenths of the substance of all animals and plants is oxygen, hydrogen, carbon, and nitrogen—the very elements which make up the entire ocean and air, and enter largely into the composition of the continents. The human body, which has essentially the same chemical composition as the bodies of animals in general, is made up of four solids, five gases, and seven metals—in all, sixteen elements of the something like seventy which constitute the entire planet. ‘In the past, man appeared to be a creature foreign to the earth, and placed upon it as a transitory inhabitant by some incomprehensible power. The more perfect insight of the present day sees man as a being whose development has taken place in accordance with the same laws as those that have governed the development of the earth and its entire organisation—a being not put upon the earth accidentally by an arbitrary act, but produced in harmony with the earth’s nature, and belonging to it as do the flowers and the fruits to the tree which bears them.’ Animals are not outside of, nor distinct from, the universe, as one might suspect who has listened much to the recital of tradition so long accepted as science. They are more or less detached portions of the planet earth which move over its surfaces and through its fluids and multiply, but which in their phenomena obey the same laws of chemistry and physics as those in accordance with which the rest of the universe acts. Animals are moulds through which digressing matters from the soil, sea, and sky pass on rounds of eternal itineracy.