Presuming that there is not a particle of evidence as yet established in favour of the supposition known as the doctrine of abiogenesis, it does not follow that no such evidence ever will, or ever can, be forthcoming. The advancement of science is continually doing away with harsh, abrupt outlines, and revealing the softest shades of transition in the varied scenery of nature. Between organic and inorganic matter, between the inert and the living mass, the line of separation has been hitherto, to our minds, the hardest and sharpest of all. We have indeed become so accustomed to this violation of the cosmos, this harsh interruption to the continuous order of nature, and to the simplicity of its general plan, that we are apt to be rather annoyed than pleased with the first efforts made to prove them only imaginary. There is a dignity about life which requires, it is thought, to be defended from too close a proximity in character to the chemical solids and liquids amongst which it makes its appearance, even though the life whose dignity is thus maintained exhibit little more than the functions of a stomach, or be presented in the somewhat dull animation of a chrysalis and the torpor of a slug.

A Wellingtonia gigantea, with its stupendous height and graceful form, with its bark and wood, and sap and pith, and cones and innumerable spikelets, seems wonderfully noble and vastly superior in the scale of creation to a spoonful of salt; yet every one of the tiny grains has, so far as we know, full as much sense and as much power of enjoyment as the stately tree. The mineral and the vegetable are, in fact, alike destitute of any qualities on which a comparison of dignity can properly be founded. The organic depends ultimately upon the inorganic for its nutriment. It is itself ultimately reduced to the inorganic. It does not, therefore, seem incredible that living organisms, simpler perhaps than any yet detected by the microscope, should be or should have been produced without generation proper by the mere combining of inorganic materials.

This is the hypothesis of Spontaneous Generation, so called, or abiogenesis, unproved and extremely difficult of proof, but precisely filling that gap in the order and continuity of nature which is so puzzling without it.

Practically it makes no difference to the theory of development whether the simple organisms from which that theory supposes the more complicated to be derived, originated at a single era or at several. The theory does not deny the perpetuation throughout vast ages of extremely simple organisms. To the general cohesion of the theory, therefore, it is unimportant whether we affiliate each of these living motes to a parent like itself, or to a combination of chemical substances previously without life.

Considering the vast results attributed to the principle of variability, it has been thought strange that any organisms should through great cycles of time have escaped its operation, and transmitted their original simplicity to an endless succession of descendants.

On the hypothesis of spontaneous generation working continuously this difficulty would disappear; simple organisms would be continually losing their simplicity by variation, but new organisms of equal simplicity would continually appear in the world, spontaneously generated.

It might still be true that all but the least conspicuous members of the world’s population belong to a single family, or to an extremely small number of separate lines of descent. If we suppose that, as soon as the globe was fitted for living occupants, a single simple organism was spontaneously generated, or, if you please, created, or, in any other way that may be named, introduced upon the earth, the results in accordance with actual facts may be logically deduced agreeably to the various principles of the theory of development. Its descendants would multiply and replenish the earth, unchecked, in all parts suited to their conditions of existence, till all such parts were occupied. No further advance in the population of the world could then take place until some variation had occurred, making possible the occupation of new regions, or of the old regions, under new conditions. But the new species, constituted by some advantageous variation, would be likely to overrun the whole field, to the almost complete suppression of the earlier and more simple form. The distance thus gained in the race of progressive organization it would be likely not only to maintain, but greatly to increase. Its descendants would vary in more than one useful direction, till it might, as we have said, become the parent of all the conspicuous members of the earth’s population. The earliest and simplest form might still have representatives inheriting its likeness by direct descent, but unable to make their way in the world, not from wanting the power to vary, but from finding the world pre-occupied by species too powerful for them to compete with. In this way they would be restrained to their original insignificance.

Now exactly the same result would follow, if, instead of being born in what we consider the ordinary course of parentage, these simple forms were ever being spontaneously generated. They would find the world pre-occupied against their advancement in the scale of organization; they would rarely, if ever, be allowed to lead up by successive useful variations to highly organized forms; and if ever, only in periods of time so enormous as to perplex the acutest human understanding.

What is commonly supposed to be the Biblical theory of Creation, is in truth a theory of spontaneous generation, only multiplying a million-fold the difficulty, if it be a difficulty, involved in that hypothesis. Unless we suppose the globe to have always existed, and always to have been tenanted by creatures endowed with life, we are forced to believe in the occurrence at some time or other of what, in the language of science, must have been spontaneous generation. As there is no historical reason for confining such an occurrence to any particular era; as science can give no reason why, if it happened once, it should not happen an indefinite number of times; as all analogy is in favour of uniform laws of nature rather than exceptional surprises; and, lastly, as numerous phenomena that have to do with the reproduction and maintenance of life are all continuous, and not interjectional—it seems at least an open question whether the origin of life itself may not also be sometimes, or even continually repeated. For, imagine what conditions we will to have prevailed when the elementary substances coalesced, out of which were compounded the first living being, it is difficult to imagine that the same conditions should never have recurred to produce a similar result, since the conditions are so far limited, that they must have been consistent, not only with the birth, but with the life after its birth, of that most antique animalcule. So many wonderful and hitherto unsuspected effects in the working of Nature have of late years been unveiled, so much of marvellous analysis successfully carried out, that it would surely be superstitious to despair of finding fresh links in the chain that binds together the lifeless and the living. Experiments in this direction may hitherto have failed from want of skill or care, or proper means at the command of those who conducted them. Yet it is not too much to ask of men renowned in science, that in pointing out the errors, they should abstain from discouraging the efforts.

Let it not be thought irreligious to anticipate the possible establishment of the supposition now under discussion. It cannot be irreverent to think that the bestowal of life upon a particle of matter too minute for human eye to see, requires no more special apparatus than that allotted to the exquisite crystals of the frost. ‘Out of whose womb came the ice? and the hoary frost of heaven, who hath gendered it?’ Yet in the workmanship of these a Divine hand is to the full as visible as in a diatom or a puff-ball. That the life-giving energy should have been exhausted in a single effort, is contrary beyond doubt to the analogy of religion, whatever may be thought of the analogy of nature.

On the other hand, let it not be thought unscientific to advocate the claims of an unproved hypothesis. It is the nature of hypotheses to be unproved. As they gather proof, the hypothetical becomes a theory. At length the theory goes on to demonstration. The use of hypotheses has often been explained. The human mind is easily exhausted by the observation of numerous incoherent facts. It is impelled to arrange and classify, to find some thread or threads of association on which the facts may be strung, some principle on which they may be parcelled out into groups. The arrangement may be erroneous, the explanatory principle untrue; they may be so plausible, so apparently satisfactory, so fascinating withal in general aspect, as for a long time to hinder the real solution of great problems; and nevertheless it may be judged that their services in the advancement of knowledge far outweigh the hindrances caused by the too servile acceptance accorded them. The foibles of a great writer may long infect the literature which his greatness has ennobled. A constitution grandly conceived in proportion to the moral and social ideas prevailing at the time of its conception may be clung to with servility long after it has been outstripped by the progress of civilization. But neither the genius of the poet nor the skill of the lawgiver could be spared in its own day and generation; neither could have been sacrificed to prevent the follies of the plagiarist, or the dulness of eyes that in after ages might read the letter without discerning the spirit.

We may almost say that a bad hypothesis is better than none; but a wrong hypothesis need not be a bad one. It may tend so to group around it the facts contributed by supporters and opponents, that when the real explanation of them all comes to be suggested, the fraternization of the confronting armies may be easy, and the truth be greeted and acknowledged with general acclaim.