We actually see natural agents now at work around us, producing results which counterfeit life, if they do not constitute it. Many substances crystallize into shapes bearing a strong resemblance to vegetable forms, as in the well known chemical experiment producing the _arbor Dianae_. The passage of the electric fluid leaves marks that are like the branches and foliage of a tree, and the same fluid exerts a direct influence on the germination of plants. Some of the proximate principles of vegetable and animal bodies, such as urea and alantoin, are said to have been produced artificially by the chemist; and in the combination of the simple elements, such as carbon and oxygen, into these proximate principles, it is now acknowledged that there is no violation of the ordinary laws of chemical affinity. The origin of all vegetable and animal life, so far as it can be traced, is in germinal vesicles, or little cells containing granules. Such are the ova of all animals; and both vegetable and animal tissues are entirely formed from them. When the parent cells come to maturity, they burst and liberate the granules, which immediately develope themselves into new cells, thus repeating the life of their original. Now, it has been asserted, that globules can be produced in albumen by electricity; and _if these globules are true germinal vesicles_, the difficult problem of producing life by artificial means is entirely solved. But the burden of this part of the theory rests on the evidence that has been produced of late years to favor the doctrine of equivocal generation, or the production of living beings without the agency, either direct or indirect, of parents of the same species. Can such beings, _orphans_ in the strictest sense, now be produced or discovered? We have not space to repeat our author's argument on this difficult mooted question in science, nor is it necessary; he sums up the evidence on his own side, and of course finds it satisfactory, though the weight of authority is against him. He adduces the experiments of Mr. Crosse, repeated by Mr. Weekes, who claim to have produced animalcules in considerable numbers, of a species before unknown, by passing a voltaic current through silicate of potash, and through nitrate of copper. The existence of _entozoa_, or parasitic animals, found in the interior of the bodies of other animals, and found nowhere else, is thought to support the same doctrine. The question is, How came they there? Being too large, either in their perfect form, or in the egg, to have passed through the capillary blood-vessels, how came they within the body of another animal,--itself but a few weeks or a few days old, or even in the embryo stage,--unless they were created there without parentage of their own species?