Vestiges Of The Natural History Of Creation Part 6

This might be done by the force of certain external conditions operating upon the parturient system. The nature of these conditions we can only conjecture, for their operation, which in the geological eras was so powerful, has in its main strength been long interrupted, and is now perhaps only allowed to work in some of the lowest departments of the organic world, or under extraordinary casualties in some of the higher, and to these points the attention of science has as yet been little directed. But though this knowledge were never to be clearly attained, it need not much affect the present argument, provided it be satisfactorily shewn that there must be some such influence within the range of natural things.

To this conclusion it must be greatly conducive that the law of organic development is still daily seen at work to certain effects, only somewhat short of a transition from species to species. s.e.x we have seen to be a matter of development. There is an instance, in a humble department of the animal world, of arrangements being made by the animals themselves for adjusting this law to the production of a particular s.e.x. Amongst bees, as amongst several other insect tribes, there is in each community but one true female, the queen bee, the workers being false females or neuters; that is to say, s.e.x is carried on in them to a point where it is attended by sterility.

The preparatory states of the queen bee occupy sixteen days; those of the neuters, twenty; and those of males, twenty-four. Now it is a fact, settled by innumerable observations and experiments, that the bees can so modify a worker in the larva state, that, when it emerges from the pupa, it is found to be a queen or true female. For this purpose they enlarge its cell, make a pyramidal hollow to allow of its a.s.suming a vertical instead of a horizontal position, keep it warmer than other larvae are kept, and feed it with a peculiar kind of food. From these simple circ.u.mstances, leading to a shortening of the embryotic condition, results a creature different in form, and also in dispositions, from what would have otherwise been produced.

Some of the organs possessed by the worker are here altogether wanting. We have a creature "destined to enjoy love, to burn with jealousy and anger, to be incited to vengeance, and to pa.s.s her time without labour," instead of one "zealous for the good of the community, a defender of the public rights, enjoying an immunity from the stimulus of s.e.xual appet.i.te and the pains of parturition; laborious, industrious, patient, ingenious, skilful; incessantly engaged in the nurture of the young, in collecting honey and pollen, in elaborating wax, in constructing cells and the like!--paying the most respectful and a.s.siduous attention to objects which, had its ovaries been developed, it would have hated and pursued with the most vindictive fury till it had destroyed them!" {215} All these changes may be produced by a mere modification of the embryotic progress, which it is within the power of the adult animals to effect. But it is important to observe that this modification is different from working a direct change upon the embryo. It is not the different food which effects a metamorphosis. All that is done is merely to accelerate the period of the insect's perfection. By the arrangements made and the food given, the embryo becomes sooner fit for being ushered forth in its imago or perfect state. Development may be said to be thus arrested at a particular stage--that early one at which the female s.e.x is complete. In the other circ.u.mstances, it is allowed to go on four days longer, and a stage is then reached between the two s.e.xes, which in this species is designed to be the perfect condition of a large portion of the community. Four days more make it a perfect male. It is at the same time to be observed that there is, from the period of oviposition, a destined distinction between the s.e.xes of the young bees. The queen lays the whole of the eggs which are designed to become workers, before she begins to lay those which become males. But probably the condition of her reproductive system governs the matter of s.e.x, for it is remarked that when her impregnation is delayed beyond the twenty-eighth day of her entire existence, she lays only eggs which become males.

We have here, it will be admitted, a most remarkable ill.u.s.tration of the principle of development, although in an operation limited to the production of s.e.x only. Let it not be said that the phenomena concerned in the generation of bees may be very different from those concerned in the reproduction of the higher animals. There is a unity throughout nature which makes the one case an instructive reflection of the other.

We shall now see an instance of development operating within the production of what approaches to the character of variety of species.

It is fully established that a human family, tribe, or nation, is liable, in the course of generations, to be either advanced from a mean form to a higher one, or degraded from a higher to a lower, by the influence of the physical conditions in which it lives. The coa.r.s.e features, and other structural peculiarities of the negro race only continue while these people live amidst the circ.u.mstances usually a.s.sociated with barbarism. In a more temperate clime, and higher social state, the face and figure become greatly refined. The few African nations which possess any civilization also exhibit forms approaching the European; and when the same people in the United States of America have enjoyed a within-door life for several generations, they a.s.similate to the whites amongst whom they live.

On the other hand, there are authentic instances of a people originally well-formed and good-looking, being brought, by imperfect diet and a variety of physical hards.h.i.+ps, to a meaner form. It is remarkable that prominence of the jaws, a recession and diminution of the cranium, and an elongation and attenuation of the limbs, are peculiarities always produced by these miserable conditions, for they indicate an unequivocal retrogression towards the type of the lower animals. Thus we see nature alike willing to go back and to go forward. Both effects are simply the result of the operation of the law of development in the generative system. Give good conditions, it advances; bad ones, it recedes. Now, perhaps, it is only because there is no longer a possibility, in the higher types of being, of giving sufficiently favourable conditions to carry on species to species, that we see the operation of the law so far limited.

Let us trace this law also in the production of certain cla.s.ses of monstrosities. A human foetus is often left with one of the most important parts of its frame imperfectly developed: the heart, for instance, goes no farther than the three-chambered form, so that it is the heart of a reptile. There are even instances of this organ being left in the two-chambered or fish form. Such defects are the result of nothing more than a failure of the power of development in the system of the mother, occasioned by weak health or misery. Here we have apparently a realization of the converse of those conditions which carry on species to species, so far, at least, as one organ is concerned. Seeing a complete specific retrogression in this one point, how easy it is to imagine an access of favourable conditions sufficient to reverse the phenomenon, and make a fish mother develop a reptile heart, or a reptile mother develop a mammal one. It is no great boldness to surmise that a super-adequacy in the measure of this under-adequacy (and the one thing seems as natural an occurrence as the other) would suffice in a goose to give its progeny the body of a rat, and produce the ornithorynchus, or might give the progeny of an ornithorynchus the mouth and feet of a true rodent, and thus complete at two stages the pa.s.sage from the aves to the mammalia.

Perhaps even the transition from species to species does still take place in some of the obscurer fields of creation, or under extraordinary casualties, though science professes to have no such facts on record. It is here to be remarked, that such facts might often happen, and yet no record be taken of them, for so strong is the prepossession for the doctrine of invariable like-production, that such circ.u.mstances, on occurring, would be almost sure to be explained away on some other supposition, or, if presented, would be disbelieved and neglected. Science, therefore, has no such facts, for the very same reason that some small sects are said to have no discreditable members--namely, that they do not receive such persons, and extrude all who begin to verge upon the character. There are, nevertheless, some facts which have chanced to be reported without any reference to this hypothesis, and which it seems extremely difficult to explain satisfactorily upon any other. One of these has already been mentioned--a progression in the forms of the animalcules in a vegetable infusion from the simpler to the more complicated, a sort of microcosm, representing the whole history of the progress of animal creation as displayed by geology. Another is given in the history of the Acarus Crossii, which may be only the ultimate stage of a series of similar transformations effected by electric agency in the solution subjected to it. There is, however, one direct case of a translation of species, which has been presented with a respectable amount of authority. {221} It appears that, whenever oats sown at the usual time are kept cropped down during summer and autumn, and allowed to remain over the winter, a thin crop of rye is the harvest presented at the close of the ensuing summer. This experiment has been tried repeatedly, with but one result; invariably the secale cereale is the crop reaped where the avena sativa, a recognised different species, was sown. Now it will not satisfy a strict inquirer to be told that the seeds of the rye were latent in the ground and only superseded the dead product of the oats; for if any such fact were in the case, why should the usurping grain be always rye? Perhaps those curious facts which have been stated with regard to forests of one kind of trees, when burnt down, being succeeded (without planting) by other kinds, may yet be found most explicable, as this is, upon the hypothesis of a progression of species which takes place under certain favouring conditions, now apparently of comparatively rare occurrence. The case of the oats is the more valuable, as bearing upon the suggestion as to a protraction of the gestation at a particular part of its course. Here, the generative process is, by the simple mode of cropping down, kept up for a whole year beyond its usual term. The type is thus allowed to advance, and what was oats becomes rye.

The idea, then, which I form of the progress of organic life upon the globe--and the hypothesis is applicable to all similar theatres of vital being--is, THAT THE SIMPLEST AND MOST PRIMITIVE TYPE, UNDER A LAW TO WHICH THAT OF LIKE-PRODUCTION IS SUBORDINATE, GAVE BIRTH TO THE TYPE NEXT ABOVE IT, THAT 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 a simple and modest character. Whether the whole of any species was at once translated forward, or only a few parents were employed to give birth to the new type, must remain undetermined; but, supposing that the former was the case, we must presume that the moves along the line or lines were simultaneous, so that the place vacated by one species was immediately taken by the next in succession, and so on back to the first, for the supply of which the formation of a new germinal vesicle out of inorganic matter was alone necessary. Thus, the production of new forms, as shewn in the pages of the geological record, has never been anything more than a new stage of progress in gestation, an event as simply natural, and attended as little by any circ.u.mstances of a wonderful or startling kind, as the silent advance of an ordinary mother from one week to another of her pregnancy. Yet, be it remembered, the whole phenomena are, in another point of view, wonders of the highest kind, for in each of them we have to trace the effect of an Almighty Will which had arranged the whole in such harmony with external physical circ.u.mstances, that both were developed in parallel steps--and probably this development upon our planet is but a sample of what has taken place, through the same cause, in all the other countless theatres of being which are suspended in s.p.a.ce.

This may be the proper place at which to introduce the preceding ill.u.s.trations in a form calculated to bring them more forcibly before the mind of the reader. The following table was suggested to me, in consequence of seeing the scale of animated nature presented in Dr.

Fletcher's Rudiments of Physiology. Taking that scale as its basis, it shews the wonderful parity observed in the progress of creation, as presented to our observation in the succession of fossils, and also in the foetal progress of one of the princ.i.p.al human organs.

{224} This scale, it may be remarked, was not made up with a view to support such an hypothesis as the present, nor with any apparent regard to the history of fossils, but merely to express the appearance of advancement in the orders of the Cuvierian system, a.s.suming, as the criterion of that advancement, "an increase in the number and extent of the manifestations of life, or of the relations which an organized being bears to the external world." Excepting in the relative situation of the annelida and a few of the mammal orders, the parity is perfect; nor may even these small discrepancies appear when the order of fossils shall have been further investigated, or a more correct scale shall have been formed.

Meanwhile, it is a wonderful evidence in favour of our hypothesis, that a scale formed so arbitrarily should coincide to such a nearness with our present knowledge of the succession of animal forms upon earth, and also that both of these series should harmonize so well with the view given by modern physiologists of the embryotic progress of one of the organs of the highest order of animals.

TABLE {226}

Table shows: scale of animal kingdom (the numbers indicate orders); order of animals in; ascending series of rocks; foetal human brain resembles, in

(The numbers indicate orders)

Rocks: 1. Gneiss and Mica Slate system Foetal: 1st month, that of an avertebrated animal;

Scale: RADIATA (1, 2, 3, 4, 5) Order: Zoophyta, Polypiaria Rocks: 2. Clay Slate and Grawacke system Foetal: 1st month, that of an avertebrated animal;

Scale: MOLLUSCA (6, 7, 8, 9, 10, 11) Order: Conchifera, Double-sh.e.l.led Mollusks Rocks: 3. Silurian system Foetal: 1st month, that of an avertebrated animal;

Scale: ARTICULATA Annelida (12, 13, 14) Rocks: 3. Silurian system Foetal: 1st month, that of an avertebrated animal;

Scale: ARTICULATA Crustacea (15, 16, 17, 18, 19, 20) Order: Crustacea, Annelida, Crustaceous Fishes Rocks: 3. Silurian system Foetal: 1st month, that of an avertebrated animal;

Scale: ARTICULATA Arachnida & Insecta (21-31) Order: Crustaceous Fishes Rocks: 4. Old Red Sandstone Foetal: 1st month, that of an avertebrated animal;

Scale: VERTEBRATA Pisces (32, 33, 34, 35, 36) Order: True Fishes Rocks: 5. Carboniferous formation Foetal: 2nd month, that of a fish;

Scale: VERTEBRATA Reptilia (37, 38, 39, 40) Order: Piscine Saurians (ichthyosaurus, &c.), Pterodactyles, Crocodiles, Tortoises, Batrachians Rocks: 6. New Red Sandstone Foetal: 3rd month, that of a turtle;

Scale: VERTEBRATA Aves (41, 42, 43, 44, 45, 46) Order: Birds Rocks: 6. New Red Sandstone Foetal: 4th month, that of a bird;

Scale: VERTEBRATA Mammalia: 47 Cetacea Order: (Bone of a marsupial animal) Rocks: 7. Oolite

Scale: VERTEBRATA Mammalia: 48 Ruminantia Order: (Bone of a marsupial animal) Rocks: 8. Cretaceous formation

Scale: VERTEBRATA Mammalia: 49 Pachydermata Order: Pachydermata (tapirs, horses, &c.) Rocks: 9. Lower Eocene

Scale: VERTEBRATA Mammalia: 50 Edentata Order: Pachydermata (tapirs, horses, &c.) Rocks: 9. Lower Eocene

Scale: VERTEBRATA Mammalia: 51 Rodentia Order: Rodentia (dormouse, squirrel, &c.) Rocks: 9. Lower Eocene Foetal: 5th month, that of a rodent;

Scale: VERTEBRATA Mammalia: 52 Marsupialia Order: Marsupialia (rac.o.o.n, opossum, &c.) Rocks: 9. Lower Eocene Foetal: 6th month, that of a ruminant;

Scale: VERTEBRATA Mammalia: 53 Amphibia Order: Marsupialia (rac.o.o.n, opossum, &c.) Rocks: 9. Lower Eocene Foetal: 6th month, that of a ruminant;

Scale: VERTEBRATA Mammalia: 54 Digitigrada Order: Digitigrada (genette, fox, wolf, &c.) Rocks: 10. Miocene Foetal: 7th month, that of a digitigrade animal;

Scale: VERTEBRATA Mammalia: 55 Plantigrada Order: Plantigrada (bear) Rocks: 10. Miocene

Scale: VERTEBRATA Mammalia: 55 Plantigrada Order: Cetacea (lamantins, seals, whales) Rocks: 10. Miocene

Scale: VERTEBRATA Mammalia: 56 Insectivora Order: Edentata (sloths, &c.) Rocks: 11. Pliocene

Scale: VERTEBRATA Mammalia: 56 Insectivora Order: Ruminantia (oxen, deer, &c.) Rocks: 11. Pliocene

Scale: VERTEBRATA Mammalia: 57 Cheiroptera Rocks: 11. Pliocene

Scale: VERTEBRATA Mammalia: 58 Quadrumana Order: Quadrumana (monkeys) Rocks: 11. Pliocene Foetal: 8th month, that of the quadrumana;

Scale: VERTEBRATA Mammalia: 59 Bimana Order: Bimana (man) Rocks: 12. Superficial deposits Foetal: 9th month, attains full human character;

The reader has seen physical conditions several times referred to, as to be presumed to have in some way governed the progress of the development of the zoological circle. This language may seem vague, and, it may be asked,--can any particular physical condition be adduced as likely to have affected development? To this it may be answered, that air and light are probably amongst the princ.i.p.al agencies of this kind which operated in educing the various forms of being. Light is found to be essential to the development of the individual embryo. When tadpoles were placed in a perforated box, and that box sunk in the Seine, light being the only condition thus abstracted, they grew to a great size in their original form, but did not pa.s.s through the usual metamorphose which brings them to their mature state as frogs. The proteus, an animal of the frog kind, inhabiting the subterraneous waters of Carniola, and which never acquires perfect lungs so as to become a land animal, is presumed to be an example of arrested development, from the same cause. When, in connexion with these facts, we learn that human mothers living in dark and close cells under ground,--that is to say, with an inadequate provision of air and light,--are found to produce an unusual proportion of defective children, {229} we can appreciate the important effects of both these physical conditions in ordinary reproduction. Now there is nothing to forbid the supposition that the earth has been at different stages of its career under different conditions, as to both air and light. On the contrary, we have seen reason for supposing that the proportion of carbonic acid gas (the element fatal to animal life) was larger at the time of the carboniferous formation than it afterwards became. We have also seen that astronomers regard the zodiacal light as a residuum of matter enveloping the sun, and which was probably at one time denser than it is now. Here we have the indications of causes for a progress in the purification of the atmosphere and in the diffusion of light during the earlier ages of the earth's history, with which the progress of organic life may have been conformable. An accession to the proportion of oxygen, and the effulgence of the central luminary, may have been the immediate prompting cause of all those advances from species to species which we have seen, upon other grounds, to be necessarily supposed as having taken place. And causes of the like nature may well be supposed to operate on other spheres of being, as well as on this. I do not indeed present these ideas as furnis.h.i.+ng the true explanation of the progress of organic creation; they are merely thrown out as hints towards the formation of a just hypothesis, the completion of which is only to be looked for when some considerable advances shall have been made in the amount and character of our stock of knowledge.

Early in this century, M. Lamarck, a naturalist of the highest character, suggested an hypothesis of organic progress which deservedly incurred much ridicule, although it contained a glimmer of the truth. He surmised, and endeavoured, with a great deal of ingenuity, to prove, that one being advanced in the course of generations to another, in consequence merely of its experience of wants calling for the exercise of its faculties in a particular direction, by which exercise new developments of organs took place, ending in variations sufficient to const.i.tute a new species. Thus he thought that a bird would be driven by necessity to seek its food in the water, and that, in its efforts to swim, the outstretching of its claws would lead to the expansion of the intermediate membranes, and it would thus become web-footed. Now it is possible that wants and the exercise of faculties have entered in some manner into the production of the phenomena which we have been considering; but certainly not in the way suggested by Lamarck, whose whole notion is obviously so inadequate to account for the rise of the organic kingdoms, that we only can place it with pity among the follies of the wise. Had the laws of organic development been known in his time, his theory might have been of a more imposing kind. It is upon these that the present hypothesis is mainly founded. I take existing natural means, and shew them to have been capable of producing all the existing organisms, with the simple and easily conceivable aid of a higher generative law, which we perhaps still see operating upon a limited scale. I also go beyond the French philosopher to a very important point, the original Divine conception of all the forms of being which these natural laws were only instruments in working out and realizing. The actuality of such a conception I hold to be strikingly demonstrated by the discoveries of Macleay, Vigors, and Swainson, with respect to the affinities and a.n.a.logies of animal (and by implication vegetable) organisms. {232} Such a regularity in the STRUCTURE, as we may call it, of the CLa.s.sIFICATION OF ANIMALS, as is shewn in their systems, is totally irreconcilable with the idea of form going on to form merely as needs and wishes in the animals themselves dictated. Had such been the case, all would have been irregular, as things arbitrary necessarily are. But, lo, the whole plan of being is as symmetrical as the plan of a house, or the laying out of an old-fas.h.i.+oned garden! This must needs have been devised and arranged for beforehand. And what a preconception or forethought have we here! Let us only for a moment consider how various are the external physical conditions in which animals live--climate, soil, temperature, land, water, air--the peculiarities of food, and the various ways in which it is to be sought; the peculiar circ.u.mstances in which the business of reproduction and the care-taking of the young are to be attended to--all these required to be taken into account, and thousands of animals were to be formed suitable in organization and mental character for the concerns they were to have with these various conditions and circ.u.mstances--here a tooth fitted for crus.h.i.+ng nuts; there a claw fitted to serve as a hook for suspension; here to repress teeth and develop a bony net-work instead; there to arrange for a bronchial apparatus, to last only for a certain brief time; and all these animals were to be schemed out, each as a part of a great range, which was on the whole to be rigidly regular: let us, I say, only consider these things, and we shall see that the decreeing of laws to bring the whole about was an act involving such a degree of wisdom and device as we only can attribute, adoringly, to the one Eternal and Unchangeable. It may be asked, how does this reflection comport with that timid philosophy which would have us to draw back from the investigation of G.o.d's works, lest the knowledge of them should make us undervalue his greatness and forget his paternal character? Does it not rather appear that our ideas of the Deity can only be worthy of him in the ratio in which we advance in a knowledge of his works and ways; and that the acquisition of this knowledge is consequently an available means of our growing in a genuine reverence for him!

But the idea that any of the lower animals have been concerned in any way with the origin of man--is not this degrading? Degrading is a term, expressive of a notion of the human mind, and the human mind is liable to prejudices which prevent its notions from being invariably correct. Were we acquainted for the first time with the circ.u.mstances attending the production of an individual of our race, we might equally think them degrading, and be eager to deny them, and exclude them from the admitted truths of nature. Knowing this fact familiarly and beyond contradiction, a healthy and natural mind finds no difficulty in regarding it complacently. Creative Providence has been pleased to order that it should be so, and it must therefore be submitted to. Now the idea as to the progress of organic creation, if we become satisfied of its truth, ought to be received precisely in this spirit. It has pleased Providence to arrange that one species should give birth to another, until the second highest gave birth to man, who is the very highest: be it so, it is our part to admire and to submit. The very faintest notion of there being anything ridiculous or degrading in the theory--how absurd does it appear, when we remember that every individual amongst us actually pa.s.ses through the characters of the insect, the fish, and reptile, (to speak nothing of others,) before he is permitted to breathe the breath of life! But such notions are mere emanations of false pride and ignorant prejudice. He who conceives them little reflects that they, in reality, involve the principle of a contempt for the works and ways of G.o.d. For it may be asked, if He, as appears, has chosen to employ inferior organisms as a generative medium for the production of higher ones, even including ourselves, what right have we, his humble creatures, to find fault? There is, also, in this prejudice, an element of unkindliness towards the lower animals, which is utterly out of place. These creatures are all of them part products of the Almighty Conception, as well as ourselves. All of them display wondrous evidences of his wisdom and benevolence. All of them have had a.s.signed to them by their Great Father a part in the drama of the organic world, as well as ourselves. Why should they be held in such contempt? Let us regard them in a proper spirit, as parts of the grand plan, instead of contemplating them in the light of frivolous prejudices, and we shall be altogether at a loss to see how there should be any degradation in the idea of our race having been genealogically connected with them.

MACLEAY SYSTEM OF ANIMATED NATURE. THIS SYSTEM CONSIDERED IN CONNEXION WITH THE PROGRESS OF ORGANIC CREATION, AND AS INDICATING THE NATURAL STATUS OF MAN.

It is now high time to advert to the system formed by the animated tribes, both with a view to the possible ill.u.s.tration of the preceding argument, and for the light which it throws upon that general system of nature which it is the more comprehensive object of this book to ascertain.

The vegetable and animal kingdoms are arranged upon a scale, starting from simply organized forms, and going on to the more complex, each of these forms being but slightly different from those next to it on both sides. The lowest and most slightly developed forms in the two kingdoms are so closely connected, that it is impossible to say where vegetable ends and animal begins. United at what may be called their bases, they start away in different directions, but not altogether to lose sight of each other. On the contrary, they maintain a strict a.n.a.logy throughout the whole of their subsequent courses, sub-kingdom for sub-kingdom, cla.s.s for cla.s.s; shewing a beautiful, though as yet obscure relation between the two grand forms of being, and consequently a unity in the laws which brought them both into existence. So complete does this a.n.a.logy appear, even in the present imperfect state of science, that I fully expect in a few years to see the animal and vegetable kingdoms duly ranked up against each other in a system of parallels, which will admit of our a.s.signing to each species in the former the particular shrub or tree corresponding to it in the latter, all marked by unmistakable a.n.a.logies of the most interesting kind.

It is as yet but a few years since a system of subordinate a.n.a.logies not less remarkable began to be speculated upon as within the range of the animal kingdom. Probably it also exists in the vegetable kingdom; but to this point no direct attention has been given; so we are left to infer that such is the case from theoretical considerations only. We are indebted for what we know of these beautiful a.n.a.logies to three naturalists--Macleay, Vigors, and Swainson, whose labours tempt us to dismiss in a great measure the artificial cla.s.sifications. .h.i.therto used, and make an entirely new conspectus of the animal kingdom, not to speak of the corresponding reform which will be required in our systems of botany also.

The Macleay system, as it may be called in honour of its princ.i.p.al author, announces that, whether we take the whole animal kingdom, or any definite division of it, we shall find that we are examining a group of beings which is capable of being arranged along a series of close affinities, IN A CIRCULAR FORM,--that is to say, starting from any one portion of the group, when it is properly arranged, we can proceed from one to another by minute gradations, till at length, having run through the whole, we return to the point whence we set out. All natural groups of animals are, therefore, in the language of Mr. Macleay, CIRCULAR; and the possibility of throwing any supposed group into a circular arrangement is held as a decisive test of its being a real or natural one. It is of course to be understood that each circle is composed of a set of inferior circles: for example, a set of TRIBE circles composes an ORDER; a set of ORDER circles, again, forms a CLa.s.s; and so on. Of each group, the component circles are INVARIABLY FIVE IN NUMBER: thus, in the animal kingdom, there are five sub-kingdoms,--the vertebrata, annulosa, {239a} radiata, acrita, {239b} mollusca. Take, again, one of these sub-kingdoms, the vertebrata, and we find it composed of five cla.s.ses,--the mammalia, reptilia, pisces, amphibia, and aves, each of the other sub-kingdoms being similarly divisible. Take the mammalia, and it is in like manner found to be composed of five orders,--the cheirotheria, {239c} ferae, cetacea, glires, ungulata. Even in this numerical uniformity, which goes down to the lowest ramifications of the system, there would be something very remarkable, as arguing a definite and preconceived arrangement; but this is only the least curious part of the Macleay theory.