He chose workmen no bigger than a pin's head. I have spoken to you about jeweller's coral, which is made into toys or presents for ladies to adorn themselves with; but its brethren, the madrepores of the Pacific Ocean, play a very different part. They have formed in front of the shores of New Holland a barrier of reefs three hundred leagues in extent and twenty wide. What are all our buildings after this?—those pyramids and cathedrals which seem so gigantic to us? This ever-increasing wave of coral polypidoms will one day shut against navigators the entrance to one part of the sea's tropical region; and lands not to be found on the map to-day will then lie stretched out under the sun, covered with plants and animals; and this in places where ships now plough the ocean. Know, also, that a great portion of the soil which we tread under foot has no other origin. It was manufactured formerly in the sea by infinite myriads of beings, often infinitely small. Each one, whether polype or shell, produced its grain of stone, and from all these grains God, who directed their work, has made our country.

But it is time to bring this chattering to a close, for it will never end if I do not force myself to stop. I leave it with regret; but all these paths through which I have threaded my way one after another without counting them, have already made a volume which may possibly be considered too large for you. There are many other zoophytes besides the coral polypes, and all of them beautiful and curious. They all inhabit the fertile depths of the waters where God has deposited the first germs of life. I cannot describe them to you now. But to make amends, I will give you a piece of advice which will perhaps make some people stare. Ask your papa to lend you Michelet's book, The Sea, and look there

for what is said about the mysterious animals which lie hid beneath the waves. His book was not written for you as this one is and if, in spite of all my good intentions, I have not always succeeded in being as compre hensible as I meant to be, Michelet, who never thought about little people when he took up his pen, will cer tainly startle you now and then. But do not be disheartened by a word. You will find there, that which will be forever plain to you, the poesy of nature, and children comprehend that better than learned men.

LETTER XL.

THE NOURISHMENT OF PLANTS.

ONE more word before we part about the last of the eaters, about Vogetables. They will furnish you with a new and very clearly marked proof of the uniformity of the fundamental conditions to which the Author of life has subjected all organised beings.

Let us look once more at this oak, of whose manner of growth I was obliged to give you a sketch beforehand, in order to show you the ties which unite it with its immediate neighbors in the animal kingdom. How does it feed? I need not tell you this. It feeds by its roots, which suck up in the bosom of the earth the water charged with the juices which form its nourishment. Are you aware that every large branch had its subterranean fellow or representative, and that the annual shoot at the top of the tree is reproduced at the base by fresh fibres, which extend themselves in the soil of the earth, in proportion as their sisters above make their way in the air? And thus, by means of organs ever young, the life and progress of the great association is kept up, while those members whose day of work is over still remain there as the supports of the edifice. It is the same with human societies. They are sustained by what is old, but they live and progress only by what is young. The sap, then, which is the name given to the moisture or water sucked in by the young roots, having

once got into the cells of which the tissue of the fibres is composed, passes from one to another, and travels thus to the top of the tree, where it is wanted by the leaves.

There is no obvious machinery here, however, to impel it forward. It journeys on of itself, as it were, under the action of laws which have never been satisfactorily explained, but all of which are dependent on the vital force or life-power of the tree, inasmuch as without it there is no circulation. One agent, but by no means the principal, or it would act as well in a dead tree as a living one, is capillary attraction; and, if you wish to know what that is, you have only to think of what happens to a towel, if you hang it upon a peg, and leave the end of it soaking in water. Does not the "wet" seem to climb up it thread by thread, till it is damp from one end to the other? A little in this way-but these similes are very imperfect, and will not bear close application—the sap rises in a tree, stealing up branch by branch; and it is then called ascending sap.*

It arrives at last at the leaves, which it enters as our food enters our stomachs, and for the same purpose; for in them takes place, as in all true stomachs, that process

* M. Macé speaks of this sap as the blood of the tree, and of the leaves only as lungs. These statements have been modified so as to meet the fact that ascending sap consists of, and conveys the raw elements of food to, the leaves; that in the leaves this food is digested, as well as brought in contact with the air, and that it is thus converted into that nourishing fluid, the descending sap, which certainly plays the part of steward to the tree as our blood does to us, and therefore may now be called the blood of the tree. It must be remembered, however, that each tree has its own sort of steward, as the case of the Euphorbia (quoted afterwards) plainly shows. The analogy with the more general substance of blood is therefore not very complete.-TR.

of digestion by which the elements of the crude sap-food are decomposed from their first condition, and converted into a nourishing chyle; in each tree of a sort" after its kind."

But more than this. Like the outer coat of the earthworm, the coat of the leaf affords a passage to air and moisture through its surface; and here, therefore, takes place that mysterious exchange which is everywhere the essential condition of life. Here is the charcoal-market as before, only the bargainers have changed parts. The air, which in the other case received the carbon, delivers it up, now, and receives oxygen in exchange; exactly the reverse of its traffic with animals. In other words, the tree inhales through its leaves the carbonic acid gas thrown into the atmosphere by our lungs. On its own responsibility it breaks through the alliance between the carbon and oxygen contracted in our organs; keeps the carbon for its own use, to restore it to us another day under the form of wood, or, by the aid of the charcoalburner, in the pure and simple state of charcoal; and sets at liberty the oxygen, which once more goes off in search of new lungs and a fresh alliance. Thus a constant equilibrium is maintained in the atmosphere; and thus, by a system of perpetual rotation or everlasting merry-go-round, the same substances serve, indefinitely, to support life of every opposite description.

Now there are two things to be remembered in this inverted respiration of vegetables. In the first place, it occurs only in the parts which are green. Flowers, fruit, the root, and every part of any other color, do as we do when we breathe; i. e. deprive the air of its oxygen, charging it with carbonic acid instead. For which reason, by-the-by, we ought not to keep flowers in a bed room at night. Charming as they are, they are poisoners,