A vast number of changes in plants and animals are superficial and in no way vital. It is hard to find two leaves of the same tree that will exactly coincide in all their details; but a difference that was in some way a decided advantage would tend to be inherited and passed along. It is said that the rabbits in Australia have developed a longer and stronger nail on the first toe of each front foot, which aids them in climbing over the wire fences. The aye-aye has a specially adapted finger for extracting insects from their hiding-places. Undoubtedly such things are inherited. The snowshoes of the partridge and rabbit are inherited. The needs of the organism influence structure. The spines in the quills in the tails of woodpeckers, and in the brown creeper, are other cases in point. The nuthatch has no spines on its tail, because it can move in all directions, as well with head down as with head up. I have read of a serpent somewhere that feeds upon eggs. As the serpent has no lips or distendable cheeks, and as its mechanism of deglutition acts very slowly, an egg crushed in the mouth would be mostly spilled. So the eggs are swallowed whole; but in the throat they come in contact with sharp tooth-like spines, which are not teeth, but downward projections from the backbone, and which serve to break the shells of the eggs. Radical or vital variations are rare, and we do not witness them any more than we witness the birth of a new species. And that is all there is to Natural Selection. It is a name for a process of elimination which is constantly going on in animate nature all about us. It is in no sense creative, it originates nothing, but clinches and toughens existing forms. The mutation theory of De Vries is a much more convincing theory of the origin of species than is Darwin's Natural Selection. If things would only mutate a little oftener! But they seem very reluctant to do so. There does seem to have been some mutation among plants,--De Vries has discovered several such,--but in animal life where are the mutants? When or where has a new species originated in this way? Surely not during the historic period. Fluctuations are in all directions around a center--the mean is always returned to; but mutations, or the progressive steps in evolution, are divergent lines away from the center. Fluctuations are superficial and of little significance; but mutations, if they occur, involve deep-seated, fundamental factors, factors more or less responsive to the environment, but not called into being by it. Of the four factors in the Darwinian formula,--variation, heredity, the struggle, and natural selection,--variation is the most negligible; it furnishes an insufficient handle for selection to take hold of. Something more radical must lead the way to new species.