But what is the resolution of this problem which the author of the Vestiges proposes? Assuredly not one which indicates the boldness of advancing science, but one of those hardy conjectures which are permitted to arise only in the infancy of a science, and which show how clear the field is, hitherto, of certain knowledge—how open to the very wantonness of speculation. Very little has been done towards determining the laws of life, and therefore the space is still free to those busy dreamers, who are to science what constructors of Utopias are to history and politics. His solution is simple enough, and with good reason may it be simple, since it depends on nothing but the will of its framer. The germ of life—that primary cell with its granule, in which some physiologists have detected the first elementary form of life—he finds to be a product of chemistry. From this germ, cell, or animalcule, or whatever it may be called, has been developed, in succession, all the various forms of existence—each form having, at some propitious moment, given birth to the form just above it, which again has not only propagated itself, but produced an offspring of a still higher grade in the scale of creation. Thus the introduction of life, and the various species of animals, is easily accounted for. "It has pleased Providence to arrange, that one species should give birth to another, till the second highest gave birth to man, who is the very highest."—(P. 234.) Under favourable skies, some remarkable baboon had, we presume, a family of Hottentots, whose facial angle, we believe, ranks them, with physiologists, next to the brute creation; these grew, and multiplied, and separated from the tribes of the Simiæ; under a system of improved diet, and perhaps by change of climate, they became first tawny, and then white, and at last rose into that Caucasian family of which we here, in England, boast ourselves to be distinguished members.
Such a solution as this most people will at once regard as utterly unworthy of serious consideration. This progressive development is nowhere seen, and contradicts all that we do see; for no progeny, even amongst hybrids, was ever known to be of a superior order, in the animal creation, to both its parents. Such a proposed origin of the human race would be sufficient, with most of us, for its condemnation. "Give us at least," we exclaim, "a man to begin with—some savage and his squaw—some Iceland dwarf if you will, wrapt in his nutritious oils—something in the shape of humanity!" In short, it is a thing to be scoffed away, and deserving only of a niche in some future Hudibras. But although the theory is thus rash and absurd, and requires only to be stated to be scouted, the author, in his exposition of it, advances some propositions which are deserving of attention, and for this reason it is we propose to give to his arguments a brief examination.
The theory divides itself into two parts—the production of organic life from the inorganic world; and the progressive development of the several species from the first simple elementary forms of life.
Spontaneous, or, as our author calls it, aboriginal generation, is a doctrine neither new, nor without its supporters. But unfortunately for his purposes, the class of cases of spontaneous generation which appear to be at all trustworthy, are those in which the animalcule, or other creatures, have been produced either within living bodies, (entozoa,) or from the putrefaction of vegetable or animal life, the decay and dissolution of some previous organization. Here life still produces life, though like does not produce like. It is well known that, amongst some of the lower class of animals, as amongst certain of the polypi, reproduction is nothing more than a species of growth; a bud sprouts out of the body, which, separating itself, becomes a new animal. With such an analogy before us, there appears nothing very improbable in the supposition that entozoa, and other descriptions of living creatures, should be produced from the tissues of the higher animals, either on a separation of their component parts when they decay, or on a partial separation when the animal is inflicted with disease. We make no profession of faith on this subject; we content ourselves with observing, that this class of cases, where the evidence is strongest, and approaches nearest to conviction, lends no support whatever to our author's hypothesis, and provides him with no commencement of vital phenomena. Of cases where life has been produced by the operation of purely chemical laws on inorganic matter, there are certainly none which will satisfy a cautious enquirer.
If Mr Crosse or Mr Weekes produce a species of worm by the agency of electricity, it is impossible to say that the germ of life was not previously existing in the fluid through which the electricity passed. When lime is thrown upon a field, and clover springs up, it is the far more probable supposition that the seed was there, but owing to ungenial circumstances had not germinated; for no one who has mentioned this fact has ventured to say that the experiment would always succeed, and that lime thrown upon a certain description of soil would in all parts of the world produce clover. Not to add, that it would be strange indeed if such an instance were solitary, and that other vegetation should not be produced by similar means.[3]
Vegetable and animal life, we ought here to mention, are considered by our author as both derived from the same elementary germ which branches out into the two great kingdoms of nature; so that it is of equal importance to him to find a case of spontaneous generation amongst the plants as amongst the animals. We must, therefore, extend the observation we made on a certain class of cases amongst animals, to an analagous class of supposed cases of spontaneous generation amongst vegetables. If that downy mould, for instance, which the good housewife finds upon her pots of jam, be considered as a vegetable, and be supposed to have grown without seed, it would be somewhat analagous to the entozoa amongst animals; it would be a vegetation produced by the decay of a previous vegetation.
It is only necessary to recall to mind the instances which naturalists record of the minuteness of the seeds of life, and the manner in which they may lie for a long time concealed, in order to induce us to presume, in the majority of examples that are alleged of spontaneous generation, the previous existence of the seed or the germ. Take the following from Dr Carpenter's work on Comparative Physiology:—"Another very curious example of fungous vegetation, in a situation where its existence was not until recently suspected, is presented in the process of fermentation. It appears from microscopic examination of a mass of yeast, that it consists of a number of minute disconnected vesicles, which closely resemble those of the Red Snow, and appear to constitute one of the simplest forms of vegetation. These, like seeds, nay remain for almost any length of time in an inactive condition without losing their vitality; but when placed in a fluid in which any kind of sugary matter is contained, they commence vegetating actively, provided the temperature is sufficiently high; and they assist in producing that change in the composition of the fluid which is known under the name of fermentation."—P. 74. With such instances before us, the experiments of Messieurs Crosse and Weekes must be conducted with singular care and judgment, in order to lead to any satisfactory result.
Let us be allowed to say, that the experiments of those gentlemen excite in us no horror or alarm. A Frankenstein who produces nothing worse than a harmless worm, may surely be suffered to go blameless. Let these electricians pursue their experiments, and make all the worms they can. They will incur no very grave responsibility for such additions as they can make to that stream of life which is pouring from every crack and crevice of the earth. Some persons have a vague idea, that there is something derogatory to the lowest form of animal life to have its origin in merely inorganic elements; an idea which results perhaps not so much from any subtle and elevated conceptions of life, as from an imagination unawakened to the dignity and the marvel of the inorganic world. What is motion but a sort of life? a life of activity if not of feeling. Suppose—what indeed nowhere exists—an inert matter, and let it be suddenly endowed with motion, so that two particles should fly towards each other from the utmost bounds of the universe; were not this almost as strange a property as that which endows an irritable tissue or an organ of secretion? Is not the world one—the creature of one God—dividing itself, with constant interchange of parts, into the sentient and the non-sentient, in order, so to speak, to become conscious of itself? Are we to place a great chasm between the sentient and the non-sentient, so that it shall be derogation to a poor worm to have no higher genealogy than the element which is the lightning of heaven, and too much honour to the subtle chemistry of the earth to be the father of a crawling subject, of some bag, or sack, or imperceptible globule of animal life? No; we have no recoil against this generation of an animalcule by the wonderful chemistry of God; our objection to this doctrine is, that it is not proved.
But, proved or not, our author has still the most difficult part of his task to accomplish. From his animated globule he has to develop the whole creation of vegetable and animal life. We shall be contented with watching its development through one branch, that of the animal kingdom.
The idea of the development of the animal creation from certain primary rudiments or simple forms of life, is due, we believe, to Lamarck; and although his peculiar theory has met, and deservedly, with ridicule, we do not hesitate to say that it is far more plausible, and substantially far more rational, than that which our author has substituted. Geology reveals to us a gradual extinction of species, accompanied by a successive appearance of new species;[4] it reveals to us also that the surface of the earth has undergone great mutations; that land and sea have frequently changed places; and that the climate of the several regions of the world, owing to many causes, has greatly varied. Natural history is replete with striking accounts of the modifications produced in a race of animals by the change of climate, diet, and the enforcement of new habits; and linking all these facts together, it does not appear a very violent supposition, nor one that departs from the frequent analogies of nature, to say, that the causes which have brought about the extinction of certain species may have also operated to the development of new species. The manifest error of Lamarck was an egregious exaggeration of certain well-known truths. Because external circumstances may do much in directing the inherent power of development possessed by a given organization, he resolved that it should do every thing. The camelopard was to get his long neck by stretching for his food; and the duck her web-foot by paddling in the water. But the author before us breaks loose entirely from the region of facts; or rather he announces to us, on his own responsibility, an entirely new fact—that it is the law of animal life that each species should, from time to time, produce a brood of the species next in order of perfection or complexity of organization. With him, this development is the result merely of a law of generation which he himself has devised to meet the emergency.