expansion, it possesses the power of emitting light, which is of a white, red, or violet-blue colour, according to the force with which it acts; and it is, therefore, the origin of the prismatic colours, as also of the tints seen in the flame of candles. Light, in its turn, has likewise the power of acting upon fire, and it is thus that the sun continually produces new sources of heat. Besides, all the compound substances observed on the globe are owing to the organic powers of beings endowed with life, of which, consequently it may be said, that they are not conformable to nature, and are even opposed to it, because they unceasingly reproduce what nature continually tends to destroy. Vegetables form direct combinations of the elements; animals produce more complicated compounds by combining those formed by vegetables; but there is in every living body a power which tends to destroy it; all therefore die, each in his appointed season, and all mineral substances, and all organic bodies whatsoever, are nothing but the remains of bodies which once had life, and from which the more volatile principles have been successfully disengaged. The products of the most complex animals are calcareous substances, those of vegetables are argils or earths. Both of these pass into a siliceous state, by freeing themselves more and more from their less fixed principles, and at last are reduced to rock-crystal, which is earth in its greatest purity. Salts, pyrites, metals, differ from other minerals, only because certain circumstances have had the effect of accumulating in them, in different proportions, a greater quantity of carbonic or acidific fire.”
Lamarck’s opinion regarding the origin of living beings, and the manner in which they acquired the various organs and forms which they now possess, are well known. They were first given to the public in 1802, in a work entitled “Researches on the Organization of living Bodies, on the Cause of its Developements, and the Progress of its Composition, and on that Principle, which, by continually tending to destroy it in every Individual necessarily brings on Death.” He conceives that the egg, for example, contains nothing prepared for life before being fecundated, and that the embryo of the chick becomes susceptible of vital motion only by the action of the seminal vapour; but if we admit that there exists in the universe a fluid analogous to this vapour, and capable of acting upon matter placed in favourable circumstances, as in the case of embryos, we will then be able to form an idea of spontaneous generations. The more simple bodies, such as a monad or a polypus, are easily formed; and this being the case, it is easy to conceive how, in the lapse of time, animals of more complex structure should be produced, for it must be admitted as a fundamental law, that the production of a new organ in an animal body results from any new want or desire which it may experience. The first effort of a being just beginning to develope itself, must be to procure the means of subsistence, and hence in time there came to be produced a stomach or alimentary cavity. Other wants, occasioned by circumstances, will lead to other efforts, which in their turn will produce new organs. One of the gasteropode molluscæ, for example, may be conceived to have felt the necessity, as it moved along, of exploring by touch the bodies in its path and to have made efforts to do so with some of the anterior points of its head, which would continually direct to that point masses of the nervous fluid, as well as other liquids: from these reiterated affluences to the point in question, there would follow a gradual expansion of the nerves which terminate there; and as the nutritious and other juices likewise flow to the same point, it must necessarily happen that two or four tentacula would insensibly be produced. This is no doubt what happens in regard to all the gasteropode tribes, whose wants occasion the habit of feeling bodies by touching them with the parts of their head; and when such wants are not felt, the head remains destitute of tentacula, as may be seen in other instances, &c.4 In like manner it is the desire and the attempt to swim, that had, in time, the effect of extending the skin that unites the toes of many aquatic birds, and thus the web-foot of the gull and duck were at last produced. The necessity of wading in search of food, accompanied with the desire to keep their bodies from coming in contact with the water, has lengthened to these present dimensions, the legs of the grallæ or wading-birds; while the desire of flying has converted the arms of all birds into wings, and their hairs and scales into feathers. Changes of this nature may appear to us contrary to what falls under our observation, which leads us to suppose that the specific forms of animals are constant; but this error is entirely owing to the difficulty we experience in embracing a considerable portion of time within the scope of our observations. It is from this cause that we cannot be ourselves witnesses of these changes, and neither history nor written observations extend to sufficiently remote a date to convince us of our mistake. If we observe that the forms of the parts of animals are always perfect when viewed in relation to their use, as is really the case, it is not to be inferred that it is the form of the parts which has led them to be employed in a certain way, as zoologists assert, but that it is, on the contrary, the need of action which has produced the peculiar parts, and it is the employment of these parts which has developed them, and established a proper relation between them and their functions. To affirm that the form of the parts induced their functions, would be to leave Nature without power, incapable of producing any act, or any change in bodies; and the different parts of animals, as well as the animals themselves, as all created at first, would from that moment present as many forms as are required by the diversity of circumstances in which animals live; and it would be necessary that these circumstances should never vary, and that such should likewise be the case with the parts of each animal. Nothing, however, of this kind takes place, and nothing can be more opposite to the means which observation shows us that Nature employs to call into existence her manifold productions. It must hence appear, that what are called species do not exist in nature; that the constancy of races to which that name has been given, can only be temporary and not absolute, although they would no doubt continue the same as long as the circumstances which effect them undergo no change, and they are not forced to alter their habitudes. It is susceptible of demonstration, that if species had an absolute constancy, there would be no varieties, but naturalists cannot help acknowledging that such exist5.
Whatever changes circumstances may have produced in individuals, are all preserved by generation, and transmitted to new individuals emanating from those which have undergone these changes. Unless this were the case, Nature could never have introduced the diversity among animals which we now witness, nor a progression in the composition of their organs and faculties6.
Such is Lamarck’s theory of life, and manner of accounting for the innumerable variety of forms in which living nature now appears. If his principles were once admitted, they would not only produce the effects he ascribes to them, but it would be a matter of surprise that natural productions are not infinitely more diversified than they really are, for nothing more is necessary than time and circumstances for any one animal form to be transformed into any other—for a monad or a polypus to become indifferently a frog, an eagle, an elephant, or a man. But the two suppositions on which they rest, viz. that it is the seminal vapour which organizes the embryo, and that efforts and desires engender organs, are both so entirely arbitrary, and the latter so obviously fallacious, that very few have ever thought it worth while to attempt a formal refutation of them. It is difficult, indeed, to conceive how Lamarck could advance a theory so utterly opposed to observation and probability, and at the same time succeed so effectually in convincing himself of its truth. He must have perceived many of the inadmissible and absurd conclusions to which it led; yet he persists in maintaining it by a kind of sophistry which could impose on none but himself. He admits the value of observation and experience in the discovery of truth; but finding that they bore no testimony to the wonderful transformations he was desirous to prove, he gets rid of their evidence altogether, by alleging that they do not extend over a sufficiently lengthened period to take cognizance of these changes. The argument, therefore, on this point, virtually amounts to this, that observation gives no notice of these operations, but that instead of thence inferring that they do not take place, the proper conclusion is, that they are actually going on, and have been in progress since the creation! How indispensable unlimited time is to give an air of plausibility to Lamarck’s theory, is strikingly evinced by the fact, of which he was perfectly aware, that we have the means of comparing animals that lived upwards of two or three thousand years ago, with the same species as they exist at present, and the conformity between them is found to be complete. Numerous quadrupeds, birds, reptiles, and insects, have been found embalmed in the Egyptian cemeteries, with all the parts in such a state of preservation as to be perfectly recognizable. “It would seem,” says the
