Thus, two French philosophers, De Maillet and La Marck, about the close of the last century, en deavoured to establish as a true proposition, that all the higher orders of animals and plants have been derived by the immutable laws of nature from the first born and lowest items in the scale of physical life ; and that life itself is producible by the agency of caloric and electricity from dead matter. They also held, that all the qualities and functions of animals have been developed by natural instinct, and a tendency to progressive improvement ; and that organisation was the result of function, and not function of organisation. Their theory of life therefore was that the zoophyte, which was de veloped out of something still more simple, ex panded itself into a mollusk or crustacean—that the crustacean was developed into a fish, fishes into reptiles and birds, and these again into quadruped mammals, and the mammal into man.
This theory, so dishonouring to God and degrad ing to man, was at once rejected as an absurdity by the common sense of mankind. It has, how ever, been revived, with a little variation, by the author of The Vestiges of the Natural History of Creation,' who has, in that work, reviewed the whole world of life which has been supplied by geology and natural history, and insists that the various organic forms that are to be found upon the earth are bound up in one—a fundamental unity pervades and embraces all, collecting them from the humblest lichen up to the highest mam mifer in one system, the whole creation of which must have depended upon one law or decree of the Almighty, though it did not all come forth at one time. The idea of a separate creation for each must appear totally inadmissible ;' and he argues that the whole train of animated beings, from the simplest and oldest up to the highest and most recent, are thus to be regarded as a series of ad vances of the principle of development, which have depended upon external physical circumstances, to which the resulting animals are appropriate.' And, as to the origin of vitality, he suggests that the first step in the creation of life upon this planet was a chemico-electric operation, by which simple ger minal vesicles were produced, and that the advance from the simplest form of being to the most com plicated was through the medium of the ordinary process of generation.
These speculations, whimsical and absurd in con ception, but at the same time most mischievous in tendency, have long since been rejected by the most enlightened of our philosophers, basing their argu ments on pure scientific principles and inductive reasoning. Professor Sedgwick, in his preface to the studies of the University of Cambridge, p.
cxxviii, has pronounced that geology, as a plain succession of monuments and facts, offers one firm cumulative argument against the hypothesis of de velopment.' Agassiz, Cuvier, and Hugh Miller have been equally strong in their condemnation of the theory.
The discussion of this question has been recently revived by the publication of Dr. Darwin's Origin of Species.' In this work an attempt has been made to solve the mystery of the creation of life, by seeking to establish the proposition that every species has been produced by generation from pre viously existing species. Dr. Darwin's hypothesis (for it is nothing more), is, that as man, acting on the principle of selection, causes different animals and plants to produce varieties, so in nature there is a similar power of selection, originated and car ried on by the struggle of life, which tends to pro duce and perpetuate, by the operation of a natural law, varieties of organisms as distinct as those which man creates among domesticated animals and plants. It must be conceded that by the principle of natural selection we can account for the origin of many varieties of the same species ; but that is far short of the proposition, that an accumulation of inherited varieties may constitute a specific differ ence. No facts have yet been established to war rant the inference, that because man can produce varieties of species by selection among domesticated animals, that he could produce, or that nature has produced, by the application of the same principle, essentially distinct species. There has always, in the case of domesticated animals and plants, been a limit to man's power to produce varieties, in like manner as, in the operations of nature, the sterility of hybrids has raised a barrier against the multipli cation of species, which cannot be passed.
Dr. Darwin believes that animals have descended from at most only four or five progenitors, and adds, that analogy would lead him one step farther, viz., to the belief that all animals and plants have de scended from one prototype, and that the proba bility is that all the organic beings that have ever lived upon the earth have descended from some one primordial form, into which life was first breathed.' This admits that life has been produced upon our planet by one, if not more, divine creative fiats ; and such being the case, it is more reasonable, as well as more natural, to account for the appearance of distinct species from time to time by the exercise of similar acts of divine power, than by a vain en deavour to link together animals in relationship by descent that are wholly dissimilar in organization, and in all the habits, propensities, and instincts of their lives.