some died out and others survived; whether these survivors were modified, and, if so, by what means; why certain plants and animals are found in places not best suited to their structure; why similar forms of life are not always found under similar physical conditions, and why dissimilar plants and animals are often found under similar physical conditions; why animals have organs of no use to them; why some animals are protected, why others are not, etc. etc. We consider that these questions are answered by the theory of the Evolution of Life, and that this theory may be regarded as the fundamental truth of Biology. We propose in this essay to bring together, in as popular a manner as possible, some of the evidence in favor of this theory, endeavoring to show that the different plants and animals are linked together by transitional forms; that there has been a progress from the simple, lowly organized, to the highly complex forms of life; that the transitional stages through which a plant or an animal passes in the development from its primitive to its adult condition are permanently retained in the lower forms of life; that the development of the higher forms of life from the lower has been brought about by Natural Selection; and that Man has descended from a lower extinct form, of which the Gorilla and the Chimpanzee are the nearest living representatives.
Before discussing these different subjects, as there seems to be still some misunderstanding in reference to the views of the predecessors of Mr. Darwin, the most distinguished of the advocates of the Evolution of Life, it may be perhaps not superfluous to glance at the literature of the subject. Here and there among the writings of the ancients, one meets with passages, and even works, like those of Lucretius, from which it is evident that at different times some doctrine like that of the Evolution of Life was held by the thinkers of antiquity. Passing by the speculations of
