year's shoot. The reader will be satisfied of this fact by examining the drawing.

The Daily Wave.-According to Treviranus, the growth of trees is accelerated during the day and retarded in the evening. The principal German physiologists appear to agree as to the fact that there is such a daily acceleration and retardation of growth, though they differ a little as to the precise time of its occurrence. This daily fluctuation is by no means unreasonable; for growth can only take place through the assimilation of formative material, and this mainly depends on the sun's influence. The vital energies of plants may possibly vary with the degree of the sun's elevation above the horizon, and plants may recuperate to some extent during the night, like the animal creation. For the same reason growth will be more rapid when the sun shines, especially after rain, than when the sky is clouded.

Some of the distinguished microscopists and physiologists of Germany think that these daily pulsations of growth have also left their mark in the interior of the tree, and that the fine layers in the thick walls of the wood and bast tissues, and of the starch granules, are connected with these daily fluctuations in the growth of plants. "Starch granules are the most easily observed in the cells of the potato, where they are very large. The mode of their formation is indicated by the peculiar markings on their outer surface, each grain having a spot at one end

Grains of starch from the potato.

which is called the hilum, or ostiole, with fine concentric lines drawn around it."*

The Life Wave.-This is that grand vibration of growth

See the author's work entitled "The Plant: an Illustration of the Organic Life of the Animal."

which extends through the whole period of the life of the tree, and which carries along with it all the smaller fluctuations of each day and each year. We have shown that the growth of the different parts of a tree depends on the amount of leaf-surface put forth by each part into the atmosphere. But there is a continually increasing number of leaves developed during the first period of the life of a tree, and consequently an acceleration of growth, not only of each individual part, but of the entire tree itself in the same ratio, until the tree puts forth its maximum amount of foliage, when the wave of growth culminates. The tree has now obtained its greatest elevation and its widest spread. Thus, precisely the same accelerated and gradually retarded growth which is manifested by the unbranched first year's shoot, pervades the entire fabric of the tree. The law of each part of a tree is thus beautifully and clearly expressed in the whole tree.

It has been intimated that not only the entire tree, but each branch and branchlet has its own independent and characteristic wavelet. It is for this reason, whilst the tree is growing, that it is perpetually changing its form, year after year. The greatest individual freedom predominates. Each shoot, each smaller and greater shoot system, grows after its own fashion. Sometimes here, sometimes there, one or two branches take the lead awhile, to be overgrown and hidden from view in succeeding years by the more powerful development of the lower and surrounding branches. Each year the tree changes its form, yet such is the wonderful power of centralization and the subjection of all its parts to the law impressed on the seed, that the tree always retains the same peculiar landscape character. To nothing is more strikingly applicable than to the tree-form, what Goethe, the German poet said of Nature: "She creates eternally new forms; what there is, was yet never; what was, comes not again. All is new, and yet always the old."* These fluc

"Sie schafft ewig neu Gestalten; was da ist, war noch nie, was war, kommt nicht wieder. Alles ist neu und doch immer das Alte."

tuations in the landscape figure or outline of a growing tree, resemble the living play of a fountain which is inexhaustible in new forms, and yet remains so similar to itself, that the spectator in the distance might almost believe himself to perceive a solid form hewn out of marble.

This constancy of the form or peculiar characteristic landscape expression of the tree, through all its fluctuations, in the earlier stages of its growth, shows the predominating influence of the grand life-wave, which carries forward all the minor fluctuations of the branches, and affords the highest proof not only of the individuality of the tree, but of the organic unity of all its parts.

There is then in the development of the entire tree, one grand, all-pervading wave of growth, or an acceleration of the yearly growths made by all its parts up to a determined stage of culmination, and from thence, to the end of its life, a progressive remission follows. For the life-wave culminates when the tree has gained its maximum height and spread, and puts forth its reproductive organs or flowers. Its growth is then slowly retarded, for reproduction is always a check upon vegetation,-the vegetative efforts of each season being absorbed by the reproductive.

And now, reader, imagine yourself seated with me beneath the shade of some grand and glorious old tree. I am going to let you into the secret of a few bright guiding thoughts, which cheer me along through life. Spring has covered this tree with another generation of bright, green leaves, all of which are at work on its fabric, and usefully employed. They will soon pass away, and others will take their place, for Nature knows no backward movements. How many such generations of leaves have already expended life in building up this tree!

Reader, your position and mine on this earth resembles that of the leaves on this tree. We are only here for a little space of time. Many generations have preceded us, and coming generations will soon take our place. The wise and good of all ages have been trying to improve this

world and its inhabitants, and, as the result of their labors, we have now a social organization called civilized society. There certainly can be no question as to the necessity of further improvements. These must be founded on Nature. Whilst we live, then, let us employ ourselves usefully, and help to diffuse science, peace, prosperity, and contentment. Let us try to build up a noble social tree.

If we study the economy of labor amongst these leaves, we shall find that they "help each other along." The lower leaves on the shoot, for instance, prepare the sap or nutrient material for the leaves above them, the little twigs assist to develope the branchlets, and the branchlets aid in the growth of the branches. In point of fact, the whole tree may be regarded as a "Mutual Aid Society;" and thus should it be in this world.

The tree is all the time changing its form, and in like manner society is ever changing its aspect through all its ramifications. Through want of life-energy and industry, some are losing gradually that social position to which they were elevated by their ancestors. They are rapidly losing the sap* for which all are contending. This is now being diverted away from them to other channels, to individual shoots and branches, where there is more vital activity, for sap is always attracted to these parts; these stranger shoots are becoming more and more conspicuous in the social tree, and will soon overtop and conceal them. It is thus that the rich sometimes become poor, and the poor rich.

But there are other causes which effect great social changes in a community. Sometimes the form of a tree changes in consequence of storms; its branches are broken off by powerful winds. And what man is sure for one moment against calamity! This is so well known, that the words "in prosperity prepare for adversity" have passed into a proverb. How frequently have the fruits of years of toil and privation been lost in a single hour!

* Sap, or dollars--that circulating medium so necessary to the development of individuals and societies in civilized communities.

It has, however, been shown that the injury done to the tree is soon effaced, that when branches are thus removed, those less developed get the sap which they monopolized. And does not precisely the same law obtain in society? If any body suffers in person or pocket, somebody is sure to benefit. Hence the force of the old Scotch proverb, "It's an ill wind that blaws naebody ony luck."

But the most remarkable and interesting feature about a tree is the fact that it is a body so easily impressible. All its periodical changes from a state of rest to that of motion, those waves of growth of which we have spoken, have left an indelible impression in the solid parts of its fabric. All the bright and stormy days of its life, every wind that has shaken its foliage, and every rain-drop that has wetted its roots, have helped to mould its physical organization, and make it just what it is. We see, however, that in the figure of its leaves, the form of its branches, and the color of its flowers, it is governed by peculiar laws of life impressed on the seed, and that it possesses an internal organizing power by which it can to a certain extent form itself, notwithstanding the indelible impressions left on its organization by the events of its life.

And is it not thus with the successive generations of man? Like the flowers of the field and the trees of the forest, do not we all develope according to the same general laws running through the same cycle of life-changes-of infancy, maturity, decay, and dissolution? Yet each individual is governed by a peculiar specific law. Is there not an individuality about each of us? Hence, like the plants around us, do we not possess, to a certain extent, an organizing power within ourselves? Like the trees, we are inseparably connected with the material world, from whence our organization derives impressions. We are a part of the universe. The matter of which our bodies are composed, like that of trees and flowers, is held together by attraction, and after a while, like them, the present living generation will disappear from the landscape,-dissolved into earth and air. But not an atom perishes. The same