Creation_, which is so offensive to him, or the idea of _Eternal Generation_, which is utterly excluded by the clearest lessons of Fossil Geology, he must have recourse to the hypothesis of _Spontaneous Generation_. Hence he attempts to account for the commencement of new species both of plants and animals, in the course of the world's history, by a transmutation of species; while, for the origin of the first species, he has recourse to the same law of Development, but acting in widely different circumstances, and giving rise to what he calls "aboriginal generation," whereby the inorganic passes into the organic, and life, form, and structure, are imparted to hitherto inert materials by the action of Electricity on mucus or albumen. To accomplish this twofold purpose, he felt it necessary to insist, in the first instance, on the ordinary law of generation as the established order of _mediate_ creation; while he found it equally necessary, in the second place, to insist on those apparently exceptional cases in which the connection between the germ and the product has hitherto eluded philosophical research,--and this for the purpose of showing that the original production of plants and animals was _not similar_ to the ordinary method of their propagation in any other respect than this, that in both cases the result is brought about by Natural Laws, without the direct interposition of any supernatural cause. Now, in so far as his argument is founded on the principle of analogy,--and it is on this principle that it proceeds throughout,--we submit that it is radically vicious, and utterly inconclusive. For the vast majority of cases in which the commencement of life and organization falls under our notice being confessedly those, not of primary production, but of mediate reproduction, it is reasonable to believe that the same law governs all cases alike, whether we have been able or not to trace the origin of life to the principle of propagation, the few apparent exceptions being sufficiently accounted for by our imperfect knowledge of the causes and conditions on which they depend. Besides, the argument from analogy in favor of a primary production of life by natural causes, in so far as it is founded on the present law of hereditary transmission, is radically defective, since the two cases are widely different; the one presupposing _a primary organism of the same kind_, from which others are evolved by a law of natural succession, the other exhibiting life as a new product, resulting not from any prior organism, but from the action of _causes of a totally different kind_, which are not known to be capable of giving birth either to vegetable or animal organisms under the actual constitution of Nature.