(4) The fossil remains of extinct species of animals are found in the earth's crust which are evidently ancestors of existing species. Until the doctrine of descent was accepted there was no way of explaining the presence of these fossil remains of extinct animals in the earth's crust. It was supposed by some that the earth had passed through a series of cataclysms in which all forms of life upon the earth had been many times destroyed and many times re-created. It is now demonstrated, however, that these fossils are related to existing species, and sometimes it is possible to trace back the evolution of existing forms to very primitive forms in this way. For example, it is possible to trace the horse, which is now an animal with a single hoof, walking on a single toe, back to an animal that walked upon four toes and had four hoofs and was not much larger than a fox. It is not so generally known that it is also possible to trace man back through fossil human remains that have been discovered in the earth's crust to the time when he is apparently just emerging from some apelike form. The latest discovery of the fossil remains of man made by Dr. Dubois in Java in 1894 shows a creature with about half the brain capacity of the existing civilized man and with many apelike characteristics. Thus we cannot except even man from the theory of evolution and suppose that he was especially created, as Alfred Russel Wallace, Darwin's contemporary and colaborer, and others, have supposed.