We sometimes hear the statement that scientists are not in agreement in regard to evolution. The point of disagreement is in respect to the part played by natural selection in the development of species, and not as to whether or not evolution is a fact. The discussion is in regard to the _how_ of the fact and not the fact itself. No great scientist since Agassiz, who died in 1873, has opposed evolution. Neither does evolution teach that one species may develop into another, as that the goat may develop into the deer, or that the ape may evolve into man. For one species to become another existing species it would have to take the back track to the point where the two species began to diverge and travel the other route--which of course would be impossible. This may help in getting the idea: the larger divisions and groups of animals (fishes, reptiles, mammals, etc.) may be compared to the main or primary branches of a tree, the families and orders (as the deer, the cat, and the dog) to the secondary branches growing from the primary ones, and the species to the further divisions of the secondary branches. Now we can see that one species can no more become another--that is, any now existing--than one branch of a tree can become another. A species can, in time, if subject to the proper conditions, split into varieties which, if developed far enough, may become distinct species. But no one of these species can be said to have been evolved from a contemporary species, for all have been changed, and the stock from which they came has ceased to exist as such. Each of the existing species would have a distinct name such as, for instance, cow, bison, Cape buffalo, yak. Now suppose the fossil remains of the common ancestor of the above-named species were found--what should it be called, cow, bison, Cape buffalo, or yak? It would be neither, for it would probably differ as much or more from them as they differ among themselves. Thus is laid to rest the idea that evolution is a theory that man was evolved from, or by way of, the monkey or the ape. They are as distinct species as is man himself. GEOLOGICAL EVIDENCES OF PROGRESSIVE DEVELOPMENT All life on this globe is divided into two great classes, vegetable and animal. All animals belong to one or the other of two grand divisions: invertebrates (those without backbones) and vertebrates (the backboned). The latter class, comprising more than 30,000 known species, is subdivided into five great groups: fishes, frogs, reptiles, birds and mammals. At the top of the highest group, mammals (those which bring forth their young alive), is man. Birds and mammals were evolved from the reptiles--both offshoots of the same stock--and are contemporaneous in development and descent.