whatever may be its position, form, or mode of action; thus, the organ of vision is called the eye, and the part that bears the flower is called the peduncle. But when we examine beings as a whole, and judge of the nature of the organs in reference to the symmetrical plan on which they are constructed, this method will lead us into grievous errors. The tail of the kangaroo serves the animal as a leg, yet nobody denies that it is still a tail; the nose of the elephant, prolonged to a great length, performs the office of a true hand; and the teeth implanted in the incisive bone, serve a purpose entirely foreign to mastication, yet none pretend to dispute the anatomical analogy of these organs with the nose and teeth of other mammifers. So too, we see the leaves of plants sometimes prolonged and changed into tendrils for the purpose of supporting the stem, though their primitive function is to elaborate the nutritious juices. The stipules, the peduncles, and even the lobes of the corolla may be converted to the same use, and every body is familiar with the leafy appearance and structure of the branches of the Indian Fig, or Prickly Pear, (Cactus Opuntia). From these examples and a host more that we might mention, we deduce the general conclusion, that it frequently happens, in consequence of a given system of structure, that a certain function, not being sufficiently performed by the organ ordinarily allotted to it, is discharged wholly or in part by another. It is this system of organization, this symmetry of the organs as compared with one another, of which a knowledge is essentially necessary to a perception of the general harmony and natural classification of beings. This symmetry of parts, which should be a prominent object of the naturalist's studies, is, in one word, the result of their relative disposition; and therefore, whenever this disposition is the same, no matter how various may be the form of particular organs in other respects, the subjects present a kind of general resemblance, that strikes the least practised eye.

Among the causes of error that are liable to mislead us in ascertaining the true nature of the organs, the principal is abortion, more or less complete, which alters their symmetry. Every body knows, that sometimes certain parts of organized beings do not receive that increase and development for which they were evidently destined, owing either to the compression of a foreign body, or a loss of part of their nourishment. This

effect may be produced by internal causes, such as caries, for instance, as well as external; but among those which prevent certain organs from receiving their full increase, it is possible that some may be the necessary consequences of the growth of another part, and will, of course, constantly occur in a given system of organization. We may, therefore, admit in theory the constant and predisposed abortion of certain organs, either wholly or in part. This is a startling doctrine to those yet uninitiated into a knowledge of the more hidden laws of organization, but is, nevertheless, as easy of proof as an abundance of the clearest facts can make it. Whoever will take the trouble to cut across the ovary of a horse-chestnut flower, soon after the petals have fallen, will find three cells and two seeds in each cell; but let him look a few weeks afterwards, when the fruit has attained its perfect growth, and three seeds or nuts are the most that can ever be found,sometimes but one. But to remove all doubt as to the fact and nature of this phenomenon, we have only to cut open an ovary every day after the period of flowering, to see some of the seeds gradually increasing, while the others are observed to remain stationary, and finally to be completely choked by the development of the first. Now, when we bear in mind that this phenomenon is constant and takes place in trees perfectly sound, are we not forced to believe, that it is owing to some circumstance in the very system of the organization of this tree? In the oak, too, we have another familiar instance of a three-celled and six-seeded ovary finally resulting in one perfect seed only. The disappearance of the sexual organs is a very common occurrence, of which an example may be witnessed in the marginal florets of the snow-ball genus, and many other plants whose flowers grow together in large masses. The question then recurs, how shall we recognise the general symmetry of plants, amid the confusion produced by these partial abortions? Some light may be obtained on this point from observing appearances denominated monstrous, an epithet commonly given to all such as differ from the habitual state of the organs, though many of them are returns of nature to the symmetrical order. Thus, to recur to an example already cited, if, by some accidental cause, the six little seeds of the horse-chestnut or oak should obtain their full growth, and present us with a fruit of six nuts or acorns, we should call it monstrous, while, in truth, it is the single-seeded fruit

that is the real monster. The Antirrhinum or Toad-flax has a personate corolla, the lower segment of which sends out a long spur, with four stamens of unequal length, and the rudiment of a fifth. In a variety of this plant called Peloria, the flower is perfectly regular, having an equal fivelobed corolla sending out five equidistant spurs, in which are five equal stamens. Here is a most singular case of a return of nature to her favorite symmetry, and no doubt can be left as to which is the real monster. The rare example of certain compound flowers, where we see the egret become leafy and assume the appearance of a true calyx, is a strong proof of the egret's being, in fact, an abortive calyx. It is well known also, that trees which have spinous branches in a dry soil, cease to have them in a fertile one, a sufficient proof that spines are abortive branches.

Another guide, less sure perhaps, but adapted to more general use, is analogy or induction. It is found solely in a knowledge of the respective positions of organs. In an Albuca, for instance, we find the entire structure of a liliaceous plant, excepting that it has only three stamens bearing anthers, while between them we observe three filaments placed precisely where stamens would be, and very similar to the existing stamens. Hence, we conclude that these filaments are abortive stamens. In the Ice-plant (Mesembryanthemum,) we find a great number of filaments disposed in several ranks, but all adhering by their bases, and attached to the same point of the calyx, the interior bearing fertile anthers, the middle having the anthers wholly or in part abortive, and the exterior being true petals. We conclude then, that in this genus, the petals are naturally abortive stamens, and from a crowd of similar facts we are led by a very powerful analogy to the belief, that the petals of all plants, as a general theorem, are only filaments of stamens, whose development is in the relation of cause or effect to the abortion of the anther. When too we see the calyx of a Valerian or Scabious evidently assuming the form of an egret or pappus, we are induced by analogy to extend this result to the compound flowers, and conclude that their pappus is only an abortive calyx. Finally, by analogy alone, we judge in a host of cases of the natural number of the parts of flowers and fruits, and are led to look carefully for those whose abortion we suspect. It is the successful use of this principle which, more than any thing else, facilitates the

study of nature, while the number of its objects are daily increased by discoveries, and constitute in fact, the true genius for Natural History.

The proximate cause of abortion is principally defect or excess of nourishment, and it may be well to consider a little farther the operation of these causes; and first, the effect of abortion by defect on the organ itself. When partial, it gives rise to inequalities between organs naturally similar, and this is the principal if not the only cause of the irregularities presented in the structure of vegetables. Every thing which has any bearing on this subject, goes to establish the conclusion, that all organized beings are regular in their intimate nature, and that abortions, variously combined, produce all the irregularities that arrest our observation. In this point of view, the slightest inequalities between organs of the same name in a plant, are important, because they tell us in language plainer than words, that we may find analogous plants where this inequality is still greater, and others where these organs, thus subject to partial abortion, have entirely disappeared. It may be received as a general principle, that wherever, in any given system of organization, there is inequality between organs of the same name, this inequality may attain its maximum, viz. the annihilation of the smallest part. When the abortion of an organ has proceeded so far as to prevent it from discharging its functions, it may be enabled, by this very circumstance, to fulfil some other functions. The abortion of the extremity of the leaf in vetches renders this part capable of performing the functions of a tendril, and abortion of the flowers of the Vine turns the peduncle to a similar use. In the same way, branches are changed into spines, and serve as defences to the plant, and the calyx of compound flowers into a pappus, which is useful, not more to the protection of the sexual organs, than the dispersion of the seed. It may happen, however, that an abortive organ, having lost the power of performing its proper function, never becomes adapted to any other, and remains without any manner of utility in the plant. In a multitude of vegetables, we find abortive stamens and pistils reduced to simple filaments or stumps, and evidently useless. Petals are sometimes found so small that they can hardly be discovered, and cannot protect the sexual organs. What purpose can those florets of certain compound flowers serve, which are invariably sterile ? In the animal kingdom, the nipples of

males, the rudiments of clavicles in the Cats, and of digits in the Ruminants, present us instances of a similar kind. These useless parts are the result of the primitive symmetry of the organization, and so far is their existence from being an argument against the general order of nature, that it furnishes one of the most striking demonstrations in its favor.

Finally, abortion may be so complete as to leave no trace whatever of the organ. Sometimes, it may be discovered, as in the seed of the oak, in the earliest periods of its existence, and observed to be gradually diminishing, while, in other cases, the organ is never found in any stage of growth. Here abortion is determined by causes so remote, that it is completed before it could be visible to us, although it may nevertheless have once existed. To illustrate this idea, let us suppose a branch of a palm, cut open from top to bottom, and our attention directed to the bunch or cluster in the centre of the section near the top, which is destined to expand the following year, then, a little lower down to the one that is to expand the second year, below that to one of the third year, and so on till we arrive at that which will expand seven years hence. Now, in certain palms, there is an entire abortion of some parts of the flower, and though this part may never be visible when the flower is developed, yet no one can deny that it may have existed in the bunch of the proximate year, or in one of the following, and that with the aid of proper instruments we might have discovered it. These abortions, like others, may be accidental or natural: when the former, we may observe the part unaffected by abortion in other individuals of the same species; when natural, predisposed as it were by the march of vegetation, we recognise the abortion only by the analogy of neighboring species. The effects of abortion on other organs will differ according to the degree to which it is carried. If it be considerable, or if the nourishment be thrown upon organs of a more variable nature, there results, not only a change of size, but of function. In double flowers, which present a remarkable example of this kind, the abortion of the anthers permits the filaments to be developed beyond measure, and become transformed into veritable petals. All that has been said of abortions by defect is equally true of abortions by excess, but in an inverse sense; and thus, while one necessarily produces the other, and both exist together, it is impossible in most cases to determine which is the cause, and which the effect. Resuming now the immeVOL. XXXVIII.-NO. 82. 7