Let us begin with the horse--one of the beasts which oftenest needs our protection. Give him the mouthful of bread whose history we have just finished. He accepts it as a treat, and needs no pressing to eat it. And if it could tell you all its adventures afterwards, you would find that you were listening to precisely the same story as your own over again; that nothing was different, nothing wanting. First of all--teeth to grind it, and a tongue to swallow it with, as a matter of course. Next a _larynx_, which hides itself to avoid it, and an oesophagus,* which receives it, just as in your case; a stomach with its _gastric juices_, the same as yours, in bagpipe form, and its _pylorus_, like your own; a _lesser intestine_, into which bile pours from a liver like yours; _chyliferous vessels_ which suck up a milky chyle, as with you; farther on a _large intestine_; and so on to the end. Nor is this all:--the horse has also a heart, with its two _ventricles_, and its double play of valves; a heart which the little girl in our tale might confidently have exhibited to the engineers as her own, but that it would have been somewhat too big, of course; into which heart, as into ours, comes _venous_ blood, to be changed afterwards to _arterial_; in lungs to which the air keeps rushing, forced thither by the see-saw action of a _diaphragm_, as faithful a servant to him as to you.

And those lungs like our own, are a charcoal market: the same exchange takes place there, of carbonic acid for oxygen, as in ours, an unanswerable proof that the stove inside the horse burns fuel in the same way as our own: and if you were to place the thermometer inside his mouth (for we are polite enough to call it his mouth), it would mark 37 1-2 degrees of heat (centigrade)--a difference from ourselves not worth mentioning. Finally, if you examine his blood, you will meet with the same _serum_ and _clot_, the whole company of _hydroclorates, phosphates, carbonates, &c._, from which we shrank before, and globules made like your own; having the same construction, and the same life, or action, if you like it better. I need scarcely add that 100 oz. of its _fibrine_ and _alb.u.men_ contain:

Of carbon......... 63 oz.

Of hydrogen........ 7

This is understood all along as being the case everywhere, from man down to the turnip; so that, like you, this n.o.ble animal, as the horse is called, is in point of fact only so much carbon, so much water, and so much air, joined to a handful of salt, which represents the earth's share in the bodies of animals.

You must confess that, if we cannot quite call the horse a fellow-creature, he is nevertheless very like us. And it is the same with all those animals which man makes use of as his servants, and which have really a sort of right to the protection of society, since they form, to a certain extent, a portion of the human family. I do not speak here of the dog, who pays his taxes, poor fellow, in his quality of friend to man.

When I think of the almost identical organization of man and his next-door neighbors, I am astonished how it could possibly have come into the head of a certain learned individual (I will not mention his name), when drawing up a plan of natural history, to give to man a separate kingdom, as a sequel to the three kingdoms already established--the mineral, vegetable, and animal. One might have forgiven Pascal if such an idea had got into his head after writing his treatise on Conic Sections; there being nothing in them to throw light on such a subject. But in a naturalist, an observer who had spent his life in the study of living creatures, the thing seems almost incredible.

Possibly he had reasons for what he did, but he certainly did not find them in the subjects of his studies.

Forgive me, my dear child, for forgetting you in this fit of indignation upon a point you cannot care much about. It leads me naturally enough to my present business, which is none of the easiest, but you must help me by paying attention. I am going to describe the _cla.s.sification of the animal kingdom_.

There are a terrible number of animals, as you know; and if we wish to study them to any real purpose, we must begin by introducing some sort of order into the innumerable crowds which throng, pell-mell, around us for observation. We should otherwise never know where to begin, or when we had come to an end.

There are many ways of setting a crowd in order, but they all go upon the same plan. The individuals composing the crowd are parcelled off into companies, each company having a distinguishing mark peculiar to those who compose it. Thus the first division is into a few large companies, which are afterwards subdivided into smaller ones, and those into others still less, until the divisions have gone far enough. And this is what is called a _cla.s.sification_.

Let us imagine, as an example, a large crowd in a public garden; I will soon cla.s.sify it for you. I shall put the men on one side and the women on the other. Then--to begin with the women--I shall subdivide them into married and single. Then among married women I shall make a company of mammas, and another of those who have no children. Among the unmarried I shall have a group of those who have never been married--girls, that is--and another of widows--those who were once married, but are so no longer. Then, following the girls, I shall separate them into tall and short. And among the short ones I shall divide the brunettes from the blondes, and so I shall get at last to a little blonde girl, whose cla.s.sification (were she a soldier) in military rank would be as follows:--_squadron_ of blondes; _company_ of shorts; _battalion_ of girls; _regiment_ of unmarried women; _division_ of women. The division of men could be carried out in the same manner; and thus we should cla.s.sify our mob into complete military order. This is easy enough, however; but the cla.s.sifying of animals is a very different affair, and I will tell you why. We ourselves require a cla.s.sification to study them by, though none was needed for their creation. The Almighty has formed them all on one uniform plan, around which He has, if I may so express it, lavished an infinity of modifications separating species from species, yet without placing between the different species those fixed barriers which we should require now to enable us to cla.s.sify them strictly. You who are learning the pianoforte have perhaps been told the meaning of a _theme_ of music--the first idea of the composer who follows it throughout the piece from one end to the other, embroidering on it, as on a bit of canvas, a thousand variations melting one into another. Such is pretty nearly, if we may venture the comparison, the way in which we can picture to ourselves the Almighty moving through the work of animal creation. Step in afterwards and divide away into regiments and battalions, if you please. Nature permits it, but she will never, to accommodate your cla.s.sifications, separate what in her is really united.

There is still a way, however, and that is to do as I did just now in the case of the crowd. To take, viz., only one _character_ (as we call a distinguishing mark in natural history), and to throw together all the individuals which possess it, the blondes, the shorts, the girls, &c. In this way it may soon be done; but what is the result? You are in one cla.s.s, your eldest sister is in another, your mamma in a third, and your brother in a different division altogether, a long way from you all.

Such a cla.s.sification is called _artificial_, and you can see at once that it is worthless.

The most natural plan is to put together those that are of the same family; and the cla.s.sifications made on this principle are called _natural_ cla.s.sifications.

It is a cla.s.sification of this sort which has been adopted for the animal kingdom. People have taken all the animals which possess in common not one character only, but a collection of characters of the most important kind, _dominant characters_, as they are called; and of these animals they have formed, to begin with, large primary groups; subdividing these afterwards according to the secondary differences, which distinguish different species in the same group from each other.

In this manner all the different sorts of animals are included in different systematic divisions of one vast whole, through which it is easy to find one's way, because there is a beginning and an end; and in which animals of the same family are always grouped side by side.

Were I to mention all the divisions of this immense cla.s.sification at once, you would find the account a little long, and not very amusing.

We will go through them by degrees therefore, and, to simplify matters, will, throughout the whole, only consider those particular characters which are connected with our special study, the nourishment of life, that is to say: so that you will always find yourself on well-known ground.

I must tell you once for all, however, that it is with this as it is with grammar. Here and there are--and it cannot be avoided--certain exceptional cases which keep protesting timidly against the arbitrariness of rules; but no matter; we must be contented with what we can get, and be grateful into the bargain to those who have given us this skillful cla.s.sification, at once so ingenious and useful, in spite of its inevitable imperfections. What is impossible is expected of n.o.body. You could not understand, even if I wished to explain it to you, the amount of science, labor and genius requisite for making out that long list, which, tiresome as it may seem to children, is absolutely beautiful in the eyes of learned men; too beautiful, perhaps, and I will tell you why when we have finished. Meantime, as the best reward we can give to those who have done us some great service is to teach their names to children, I will tell you, before bidding you good-bye, to whom we owe this cla.s.sification, the details of which I do not enter upon to-day.

In the first place, we owe the method employed in its establishment, the method of _natural cla.s.sification, i.e._, to a learned man of the last century--a learned Frenchman, Bernard de Jussieu--who tried it upon plants; another large flock by no means very easy to put in order, as you may convince yourself any day by studying botany. The man who applied this system to animals was also a learned Frenchman, the clearness of the French mind adapting them peculiarly for that sort of work. And he, too, is one of the glories of that nation. His labors and discoveries gave a perfectly new impulse to the study of nature. It was George Cuvier, whose statue you may see at Montbeliard, if you should ever go there. Not that Cuvier carried through this gigantic work alone, though the credit of it is justly his due, he having directed and inspired it. He was a.s.sisted by many. But among his a.s.sistants there was one, Laurillard, the most modest, yet the most active of all, whose name I will mention also, because, like the others, more or less celebrated, he has never had his reward. [Footnote: In the earlier editions of this work, there was, in this place, a severe reproach upon Cuvier for not having given proper credit to Laurillard. This reproach I have since learned was unjust. M.

Valenciennes himself, one of the most ill.u.s.trious of the collaborators of the great Cuvier, has written me a letter in which he defends the reputation of his friend with a warm indignation which does honor to both of them; and cites pa.s.sages in which Cuvier has spoken of Laurillard, and among others, in the third volume of the _Oss.e.m.e.nts Fossiles_, p. 32, ed. of 1822.]

It only remains for me, therefore, to let the lash, which I was laying upon the shoulders of another, fall now upon my own, and to deplore the too great facility with which I had credited, without sufficient proofs, an a.s.sertion which I had otherwise good reason to believe to be exact--coming to me, as it did, from Montbeliard himself, on the testimony, it is said, of the family of Laurillard. From this avowal, a little painful, I confess, my young readers may learn the inconvenience of rashly condemning others! As I said in the concluding pa.s.sage, which truth, only too late, now compels me to suppress--"The truth is sure to come out at last."

LETTER x.x.x.

MAMMALIA. (_Mammals_.)

Do you remember of my talking of the _vertebral column_ when I was describing that great artery, the _aorta_, to which it forms a rampart of defence? I should not have named it without explanation, but that you had only to pa.s.s your hand down your back to find out what it was. Now the _vertebral column_, or backbone, is one of those _dominant characters_ which always carries along with it a train of other points of resemblance in the animals where it is found. It has been chosen, therefore, as the rallying-point of the first great group. I must tell you beforehand that there are four of these groups, four large companies, _i.e._, which naturalists have called by various names; as Groups, Sections, Primary Divisions and even Branches; in this case comparing them to four great branches of a tree, going off in different directions from the same trunk.

And, first of all, we have to begin with the group of the _Vertebrata_--vertebrata animals--vertebrata being a word which explains itself.

Of course we ourselves belong to this group. In fact, we are at the head of it; but it descends far below us. It goes on to the frog and the fish, and includes the monkey, the ox, the fowl and the lizard; for all these creatures possess the vertebral column. The frog does not appear to be very much like us at first sight; and yet, by virtue of its vertebra, it has its points of resemblance to us, which are worth the trouble of considering. Vertebrated animals are all furnished with a head, containing a brain, which gives its orders to the whole body; they have all an internal skeleton, that is to say, a system of bones linked together, forming a solid base by which all the organs are supported. I was going to add that they have all four limbs; but here the serpent glides in to call me to order, and to hiss at our childish craving for fine-drawn divisions, in perfect order, where there is an exactly proper place for everything. However, each has, without exception, a heart, with its network of blood-vessels; red blood, under its two conditions of arterial and venous; and also a digestive tube, acting, on the whole, pretty much like our own. I do not insist, mind, upon this last point, viz., that of the digestive tube; for we shall see, by-and-by, that it is a character beyond the pale of the primary groups. It is the fundamental character of the trunk itself, which necessarily exists, therefore, in all the groups; and, as I told you in my first letter, you will find it everywhere.

This is--to let you into the secret at once--the theme on which the Great Composer has based all His infinite varieties of animal life; and herein lies the uniformity of the animal creation, that startling uniformity which has given so much offence to many learned men, and which is so obvious that it will strike you of itself, I feel sure.

But I reserve this subject to the end of my letters, when you will have heard all, and be able to judge for yourself.

It would be plunging back into confusion to attempt to examine all the vertebrated cla.s.ses at once. After making a division you must go on.

The groups have, therefore, been subdivided into _five cla.s.ses_, which we will study in succession, only naming each now: viz. _mammals_, _birds_, _reptiles_, _fish_, and _batrachians_. Do not alarm yourself at this last name: it is a Greek word, meaning simply frogs.

The mammals are our immediate neighbors. Mammalia are the animals which produce milk. They bring forth their young alive, and give suck to them as soon as they are born. This was your first nourishment, my dear child, so you yourself are a little mammal.

What I said to you in the last letter about the horse, applies pretty nearly as well to all mammals. We shall not, therefore, have any great variations to notice here. Nevertheless, as these are the animals which interest us most nearly, as they are in fact our nearest of kin, so to speak, and those with whom we have the most to do, we will now pa.s.s in review the different orders of which their cla.s.s is composed. I must explain to you that the _cla.s.ses_ are subdivided into _orders_, the orders into _families_, the families into _genera_, the genera into _species_; as in armies divisions subdivide into regiments, regiments into battalions, &c. It became necessary, moreover, to make use of special names, in order to make these subdivisions comprehensible, and the following are those which have been adopted.

ORDER 1. _Bimana (two-handed)_.

Here we may pa.s.s on at once, for we have discussed this order enough already. We are _bimane_ ourselves, since we have the distinction of possessing two hands. Yes; that is the pretty t.i.tle which the professors have been so polite as to give us, instead of leaving us simply our proper name of man. Yet it would have been very easy to do this, seeing that we are the only family, the only genus, and the only species of the order. In railway travelling, people of distinction have a reserved carriage to themselves: so we decidedly deserve an order to ourselves; but that is not quite the same as a separate kingdom. In short, you are a _bimane_; so make the best you can of it.

ORDER 2. _Quadrumana (four-handed)_.

These, as their name indicates, have four hands: two at the end of the arms, and two at the end of the legs; such are the monkeys. There is nothing to remark; they are all alike. Stay; I am wrong, though: there is something, insignificant it is true, but still pointing to deviation.

In some the canine teeth are set forward, _i.e._ project, and are longer than the rest, and some species, as the ape, for instance, have just under their cheeks convenient little pockets, which open into the mouth, and in which they can deposit a reserve of nuts to be devoured at leisure; these are called _pouches_.

It is a trifle in itself, but we have here a first example of the eccentricities of nature in the construction of animals. At one time she adds a detail; at another she suppresses one. Sometimes she is pleased to enlarge an organ, as in the canine teeth of the monkey; sometimes she reduces it; or perhaps here she makes its construction more simple; there again more complicated: but still it is always the same organ. So the dressmaker shapes the sleeves of a dress, sometimes open, sometimes closed, flat or puffed, plain or ornamented, paG.o.da-shaped or gigot-formed: but still they are all of them sleeves.

ORDER 3. _Cheiroptera (wing-handed)_.

I am quite ashamed of offering you such a word as this, my dear child.

It was a Greek fancy of the learned men, who would not condescend to use the vulgar name Bats. In the Greek, _cheir_ means hand, and _pteron_ wing. The Cheiroptera are animals with winged hands; in fact, the fingers which terminate the fore-limbs of the bat lengthen as they spread out to an extravagant extent; and are connected together by a membrane springing from the body, with which they beat the air as with a wing, and which enables them to fly with such ease that theyare often taken for birds.

But, so far from really being a bird, this curious little creature has the same internal organization as ours, and indeed comes so near us, though without looking as if it did, that a scientific man, and a very distinguished one too, placed the bat in the first family of the animal kingdom, with the monkey, and, you will hardly believe it, with man.

It is found that the bat, like man and the monkey, suckles its young at the breast; and it was this very character which Linnaeus, the leader of artificial cla.s.sification, thought of selecting as the distinguishing mark of his first family in the animal kingdom. It is true that in honor of the human race he had given that first family a much more sonorous name than our usual one of _man_--viz. _primates_, the first in rank--that is, the princes. But, alas! we were to be princes on an equality with bats; and, for my own part, I prefer being a _bimane_, and alone. I really believe that it was to put this saucy little creature back into its proper place that, at the time of the great revolution in favor of natural cla.s.sification, the conclave of professors a.s.sembled at the Botanical Gardens in Paris inflicted this horrid name of Cheiroptera on the bat, ejecting it contemptuously from the overthrown dynasty of the _primates_.

I have not been sorry to make you acquainted as we went along, with this little trait in the history of cla.s.sification; but beyond it there is really nothing particular to say about the apparatus for the nourishment of the deposed bat-princes, which is a plain proof how nearly it must be like our own. By-the-by, there is one trifling remark to be made with regard to her teeth. The bats we have in our country (France), for there are many varieties of species in the world, live on insects, which they catch in their flight by night. These insects are often enveloped in a very hard outer case, which molars like ours would have some difficulty in chewing properly; consequently the molars of our little friend are fringed with conical points, and with these she grinds down her prey without difficulty.

In America there is a large bat, the vampire, which lives on the blood of animals, and nature has armed it accordingly. It has at the extremityof its muzzle two sharp beak-like incisors, like the lancets of a surgeon. The vampire bat, which roams by night like other bats, goes straight at the large animals it sees asleep, delicately opens a vein in the throat without waking them, and sucks their blood in long draughts, taking care, by fanning them with its wings, to lull them into a cool and balmy slumber. It does not, as you see, make a savage attack on its victim: it merely inflicts a bite like that of the leech, but the result may be death. This is the best emblem I know of the sycophant, who undermines your soul while he fans your vanity; and observe, while we are on the subject, that this species has always had the art of insinuating itself among princes.

ORDER 4. _Carnivora (flesh-eaters)_.

When translated into English, this word needs no explanation. And here we have the tribe of bears, wolves, foxes, weasels, dogs, cats, tigers, lions, of all the fighting animals, _i.e._, those which steep their muzzles in blood, and live by devouring others. These have a similar apparatus for nutrition to our own; especially the bear, who, with the monkey, is the animal most nearly resembling man, seeing that he has feet like ours, with scarcely any tail, while the monkey has our hands, without specifying any other points of resemblance. Like ourselves, too, the bear is omnivorous; that is to say, it eats everything, vegetables and fruit as well as meat; and nature, which has given it our diet, has furnished it with molars almost exactly like our own. Its canine teeth alone differ from ours: they are more prominent even than those of the _quadrumana_; and this is the case with all the members of the order, in whom we find them sometimes developed into actual daggers. But those of them which are purely carnivorous have molars peculiar to themselves. The lion, for example, who does not share the bear's taste for carrots, and who would die of hunger surrounded by the honey and grapes of which the bear is so fond--the lion, who never takes anything but raw meat between his teeth, has molars furnished with sharp cutting edges, intended to slice the meat like the chopping knives used by cooks for making a hash.

The lion offers another peculiarity, which is common to him with all the _Carnivora_. Place your finger close to the lower end of your ear, and work your jaw; you will feel something hard moving backward and forward against your finger. This is where the lower jaw is set into a bone of the skull, called the _temporal_, if you care to know its name; in other words, the bone of the temple. The extremity of the jaw bends, and forms a kind of little k.n.o.b, called _condyle_, which fits into a cavity of the temporal bone. With us the cavity is not very deep, nor the k.n.o.b very large, so that it can play very freely; and it is this which allows us that second movement from side to side, of which I spoke to you formerly, and thanks to which, our little mills reduce a mouthful of bread into paste. But this freedom of action has also its inconveniences. You must never attempt to force too large an article into your mouth at once--an apple, for instance--the efforts you would then be obliged to make might easily cause the _condyle_ to slip out of its little cavity, where its hold is but slight, and to get under the _temporal bone_; and there you would be with your mouth wide open until the doctor arrived. The lion, whose voracious jaw opens like the door of an oven, so that the tamers of wild beasts have no scruple in thrusting in their whole heads, a mouthful a good deal larger than an apple; the lion, who has no doctors, would often be liable to this accident--an irremediable one in his case--if nature had not made a special provision for him. In order to secure greater firmness and strength, the second movement is in his case sacrificed by embedding the _condyles_ deeply in their cavities, where they are fastened in such a fashion that they can only move up and down, like the handles of a pair of pincers. This is a restraint which enables the jaw to be safely thrown open as wide as the fiery impulse of its terrible proprietor impels it. Less freedom, in exchange for more power, is a bargain which any one would gladly accept who plays the part of a lion!

I have here a remark to make. We have now pa.s.sed in review three orders besides our own, and have only had to point out a change in the fastenings of the jaws and in the teeth; and you will find that the same sort of modifications take place in the whole cla.s.s of mammals.

This is in fact the essentially movable and variable point in their apparatus for nutrition. The jaw and its weapons vary their character from one species to another, according to the nature of their food; but the modifications generally terminate there, _i.e._ on the threshold, as it were. The interior arrangements of the house remain otherwise much the same in all.

Here, however, in the lion, there is an interior change to be described; but not in the arrangement of the parts, only in their size; the stomach in this species being even smaller and weaker in proportion than ours, and the digestive tube more than twice as short. The digestive tube of an ordinary sized man is about seven times the length of his body, whilst that of the lion only measures three times the length of the animal. This is a natural consequence of the kind of nourishment he takes. Flesh and blood, on which he lives entirely, is concentrated _alb.u.men_, prepared beforehand in the bodies of his victims; so that no great preparation is needed here to convert it into lion's blood. A professor of chemistry, who has a good a.s.sistant, does not need a very large laboratory. This is the case with the lion; and nature, which makes nothing in vain, has here economised s.p.a.ce. Tame the monarch of the forest into a domestic animal, and change his food, and I will wager anything you please that, in the course of a few generations, his digestive tube will lengthen itself. Examine the inside of the cat, his little cousin, formed originally on the same pattern as himself, and, without having ascertained the fact myself, I am sure that, by dint of feeding it daily on sops and milk from generation to generation, its digestive tube has become more than three times the length of its body.

Here you ought to be told at once a very important fact relative to the organization of the lower animals, one which places them all very far below the order of _Bimana_, since there is such an order.

In bestowing intelligence and freedom of action on man, the Almighty has given him the unspeakable privilege of working in His footsteps--if I may presume to use the expression--of following up His work of creation as it came from His hand. Now especially that man begins to see a little more clearly into the laws of life, he has entered more directly into the possession of this almost divine privilege, which the Almighty has graciously vouchsafed him. You can even now have an ox or a sheep made to order in England, giving your dimensions, as if you were ordering a cabinet; and in a few years, if you have not asked actual impossibilities, your commission will be executed to within an inch. This is not said in reference to the _Carnivora_. But in bidding you good-bye, my dear little mammal, I could not bear to leave you under the weight of that debasing t.i.tle: I wanted also to show you your greatness.