Blackwood's Edinburgh Magazine, Volume 57, No. 354, April 1845

We are very far from intending to follow the author of the Vestiges of the Natural History of the Creation through all the sciences along which his track has led him. We shall limit ourselves to what forms the most peculiar and startling portion of his work – to his theory of the origin and development of animal life.

But for the discoveries of geology a certain philosophy might have been content to say of the animal creation, that it was the law of nature that life should beget life – that reproduction, like nutrition, to which it has been assimilated, is a part of the definition of life – and that, as to a commencement of the various tribes of animals, we are no more bound to look for this than for the commencement of any other of the phenomena of nature. From the researches, however, of geology, it is evident that there was a time when this earth revolved around the sun a barren and untenanted globe – that there was a time when life did make its first appearance, and that in different epochs of the world's existence there have flourished very different species of animals than those which now inhabit it. Here, at all events, the imagination cannot gain that imperfect repose which it finds in the contemplation of an eternal series. It is a plain historical fact, that life had a beginning on this earth, and that from time to time new forms of life, new species of vegetables and animals, have been introduced upon the scene. Here are two great facts to be accounted for, or to be left standing out, unconnected in their origin with that interlinked series of events which creation elsewhere displays. Life reproduces life, the plant its seed, the animal its young, each after its kind, such is the law; but this law itself, when was it promulgated, or when and how did it come into force and operation?

For ourselves, in the present imperfect condition of our knowledge, we are satisfied with referring life, in all its countless forms, at once to the interposing will of the Creator. We listen, however, with curiosity and attention to any theory which the naturalist or physiologist may have to propose, so he proceed in the fair road of induction. There is nothing in the laws of life which forbids, but much, on the contrary, which invites, to the same pains-taking examination which has been bestowed, with more or less success, on other phenomena of nature.

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.

Amongst the laws of life, the most conspicuous and undoubted is this – that each species reproduces itself, that like begets like. This law our author cannot of course gainsay; but he appends to it another overruling law, that from time to time, at long intervals, the like does not beget the like, but the different and superior form of organization. In other words, the old law changes from time to time. Of this novel description of law he borrows the following illustration of Mr Babbage: —

Unquestionably, what we ordinarily see of nature is calculated to impress a conviction that each species invariably produces its like. But I would here call attention to a remarkable illustration of natural law, which has been brought forward by Mr Babbage in his Ninth Bridgewater Treatise. The reader is requested to suppose himself seated before the calculating machine and observing it. It is moved by a weight, and there is a wheel which revolves through a small angle round its axis, at short intervals, presenting to the eye successively a series of numbers engraved on its divided circumference.

"Let the figures thus seen, be the series 1, 2, 3, 4, 5, &c. &c., of natural numbers, each of which exceeds its immediate antecedent by unity.

"Now, reader," says Mr Babbage, "let me ask you how long you will have counted before you are firmly convinced that the engine has been so adjusted that it will continue, whilst its motion is maintained, to produce the same series of natural numbers. Some minds are so constituted, that after passing the first hundred terms they will be satisfied that they are acquainted with the law. After seeing five hundred terms, few will doubt; and after the fifty thousandth term, the propensity to believe that the succeeding term will be fifty thousand and one, will be almost irresistible. That term will be fifty thousand and one, and the same regular succession will continue; the five millionth, and the fifty millionth term will still appear in their expected order, and one unbroken chain of natural numbers will pass before your eyes from one up to one hundred million.

"True to the vast induction which has been made the next succeeding term will be one hundred million and one; but the next number presented by the rim of the wheel, instead of being, one hundred million and two, is one hundred million ten thousand and two. The law changes."

The illustration is carried through a page or two more, but we have quoted all that is essential.

Mr Babbage makes a very useless parade here of his calculating machine. A common household clock that strikes the hours, would illustrate all that his machine can possibly illustrate. If the reader seat himself before that homely piece of mechanism, he will hear it tick for sixty minutes, when the law of the machine will change, and it will strike.

In a scientific point of view it is absurd to talk about the law of his machine. His machine partakes only of the laws of mechanics, which, we presume, are as constant there as elsewhere. Our only definition of law is, a sequence that is constant; deny its constancy, and you deny it to be law; it is a mere contradiction in terms to speak of a law that changes.

If, therefore, our author, guided by this illustration of Mr Babbage's, proclaims a law of animal life which changes of itself from time to time, he is departing from the fundamental principle of all science – he who is so zealous to reduce all phenomenon to the formula of science! Anxious to escape from an abrupt interposition of creative power, he introduces a sudden mutability in the laws themselves of nature! If it be said that he does not (although his words imply it) insist upon a single law of nature that varies at intervals, but contends for a variable result, produced by the law of reproduction acting under varied circumstances, and in co-operation with different laws – then was Mr Babbage's machine of no use whatever to him, nor did he stand in need of any peculiar illustration. There is not a class of phenomena which does not exhibit this variety of result by the diversified co-operation of laws constant in themselves. The frozen river becomes motionless; it ceases to flow; yet no one attributes any inconstancy to the laws of heat, or the laws of hydrostatics.

Quitting these abstractions, in which the writer before has shown himself no very great adept, let us enquire by what arguments he attempts to support his peculiar principles of development. That on which he appears chiefly to rely is the fact, that the embryo of one of the higher animals passes through the fœtal stages of the lower animals – the fish, the reptile, the bird – before it assumes its last definite shape. From this he would infer, that the germ of life is alike in all, and that it depends only on peculiarities of gestation whether it shall become a fish, a fowl, or a mammal. He lays particular stress on the circumstance, that the brain of the human embryo passes through these several stages.

But, 1. In order to derive any thing like an argument here, surely the whole human embryo, and not the brain only, ought to undergo these changes. But not only in man, in the other mammalia to which allusion is made, it is never the entire animal which passes through these transformations.

2. If the embryo of one of the mammalia pass through the fœtal stages of the fish and the bird, the embryo fish bears the same transitory resemblance to the fœtal condition of the bird or the mammal. So that the order here is reversed, and nothing appears proved but that some deviations of form are in all cases assumed before the final shape is adopted. And,

3. The physiologists who have made this branch of their science an especial study, tell us, as the result of their microscopic observations, that the embryo of the higher animals pursues a different course of development, from the very earliest stages, to that of the lower animals. It cannot be, therefore, according to the diagram that the author presents to us, that the same germ which is nourished up to a certain point to be fish, would, if transferred to other care and a better system of nutrition, be nourished into a bird or a mammal. If it is to be a mammal, it must be fashioned accordingly from the very beginning.

We will content ourselves with quoting, as our authority for these assertions, a passage from Dr Carpenter's work on Comparative Physiology; and we cite this author the more willingly, because he is certainly not one who is himself disposed to damp the ardour of speculation, and because the very similarity of some of his views, or expressions, renders him, at all events, an unexceptionable witness on this occasion.

"Allusion has been made to the correspondence which is discernible between the transitory forms exhibited by the embryos of the higher beings, and the permanent conditions of the lower. When this was first observed, it was stated as a general law, that all the higher animals, in the progress of their development, pass through a series of forms analogous to those encountered in ascending the animal scale. But this is not correct, for the entire animal never does exhibit such resemblance, except in a few particular cases to which allusion has already been made, (the case of the frog, and others, who undergo what is commonly called a metamorphosis.) And the resemblance, or analogy, which exists between individual organs, has no reference to their forms, but to their condition or grade of development. Thus we find the heart of the mammalia, which finally possesses four distinct cavities, at first in the condition of a prolonged tube, being a dilatation of the principal arterial trunk, and resembling the dorsal vessel of the articulated classes; subsequently it becomes shortened in relation to the rest of the structure, and presents a greater diameter, whilst a division of its cavity into two parts – a ventricle and an auricle – is evident, as in fishes; a third cavity, like that possessed by reptiles, is next formed by the subdivision of the auricle previously existing; and lastly, a fourth chamber is produced by the growth of a partition across the ventricle; and in perfect harmony with these changes are the metamorphoses presented by the system of vessels immediately proceeding from the heart. In like manner, the evolution of the brain in man is found to present conditions which may be successively compared with those of the fish, reptile bird, lower mammalia, and higher mammalia; but in no instance is there an exact identity between any of these. It is to be remembered, that every animal must pass through some change in the progress of its development, from its embryonic to its adult condition; and the correspondence is much closer between the embryonic fish and the fœtal bird, or mammal, than between these and the adult fish." – (P. 196.)

And take, also, the following short passage from the preface of the same work, where the author has been speaking of the latest discoveries of physiologists on the development of the embryo.

"Thus, when we ascend the scale of being, in either of the two organized kingdoms, we observe the principle of specialisation remarkably illustrated in the development of the germ into the perfect structure. In the lowest of each kind, the first-formed membranous expansion has the same character throughout, and the whole enters into the fully-developed structure. In higher grades the whole remains, but the organs evolved from the centre have evidently the most elevated character. In the highest none but the most central portion is persistent; the remainder forming organs of a temporary and subservient nature."

The fact that the animal kingdom exhibits a gradual progression from forms the most simple to forms the most complex, is, of course, appropriated by our author as a proof of his theory of successive development. It is well known, that whilst this scale of being is an idea which occurs to every observer, the naturalist finds insuperable difficulties in arranging the several species of animals according to such a scale. To relieve himself from these, the author has taken under his patronage what, in honour of its founder, he calls the Macleay System, in which the animal kingdom is "arranged along a series of close affinities, in a circular form;" into which circles we will excuse ourselves from entering. It is a system as confused as it is fantastic; and our author, who writes in general in a clear and lucid manner, in vain attempts to present us with an intelligible exposition of it. Arrange the animal creation how you will, in a line or in circles, there is one fact open to every observer, that however fine may be the gradations amongst the lower animals, the difference between the higher animals is very distinctly marked. It is a difference which does not at all accord with the hypothesis of our author, "that the simplest and most primitive type gave birth to the type next above it, and this again produced the next higher, and so on to the very highest, the stages of advance being in all cases very small – namely, from one species only to another; so that the phenomenon has always been of simple and modest character." Whilst he confines himself to mollusks, and suchlike obscure creatures, the phenomenon he supposes may not be very startling; but when he ascends to the higher and larger animals, whose forms and habits are well known to us – when he has to find a father for the horse, the lion, the rhinoceros, the elephant – his phenomenon, we are sure, will no longer retain its "simple and modest character."