Origin of Species Variorum

in all organic beings, seems to have felt this difficulty so strongly, that he was led to suppose that new and simple forms were continually being produced by spontaneous generation. I need hardly say that Science in her present state does not countenance the belief that living creatures are now ever produced from inorganic matter. ↑ On my theory the present existence of lowly organised productions offers no difficulty; for natural selection includes no necessary and universal law of advancement or development— it only takes advantage of such variations as arise and are beneficial to each creature under its complex relations of life. And it may be asked what advantage, as far as we can see, would it be to an infusorian animalcule— to an intestinal worm— or even to an earth-worm, to be highly organised? If it were no advantage, these forms would be left by natural selection unimproved or but little improved; and might remain for indefinite ages in their present little advanced condition. And geology tells us that some of the lowest forms, as the infusoria and rhizopods, have remained for an enormous period in nearly their present state. But to suppose that most of the many now existing low forms have not in the least advanced since the first dawn of life would be rash; for every naturalist who has dissected some of the beings now ranked as very low in the scale, must have been struck with their really wondrous and beautiful organisation.

Nearly the same remarks are applicable if we look to the great existing differences in the grades of organisation which occur within almost every great group; for instance, to the co-existence of mammals and fish in the vertebrata,— to the co-existence of man and the ornithorhynchus amongst mammalia— or of the shark and lancelet (Branchiostoma), which latter fish in the extreme simplicity of its structure .. approaches the