French Journal of Forestry, and, for comparison, we place by its side a description of the same region, only about fifty years before:

Trees and their Role in Nature.

By J. G. O. TEPPER, F.L.S., &c.,

Adelaide.

I. Primary Truths to be kept in Mind.

If one desires to arrive at an approximately correct view of natural problems one has to keep in mind certain primary laws or truths. Some of the more important are the following:

1. The unity of nature; that is, that the same laws prevail throughout, and that similar causes produced the same effects in the past as are observed now, and will do so in future.

2. That one of the principal attributes of matter is its inertia, i.e., that it neither can put itself into motion nor arrest itself when in motion.

3. That all natural phenomena are referable to matter and motion (substance and force or energy).

4. That nothing whatever is known of matter in the abstract (or absolute), no one having ever observed the molecules or atoms when isolated; all we know being aggregates or masses, of which even the minutest fragments involve considerable numbers. From the invariable behaviour of those atomic or molecular aggregates, paragraphs 1 and 3 being deduced, it follows necessarily that, as these exhibit inertia, the atoms or molecules must likewise possess the same quality.

5. Matter in motion only exhibits energy or force. According to rate of motion, its direction, intensity, simplicity, or complexity, the energy manifested differs widely in character, which becomes manifest to the observer through his sensory organs, their perceptivity being limited by the range of vibrations they are fitted for, and by their acquired or natural sensitiveness. 6. The so-called forces-gravity, light, heat, magnetism, electricity-are only forms of motions (vibrations), and nothing substantial. To the same category belongs life, or vital energy, under whose sway otherwise inert material molecules exhibit peculiar phenomena (when combined as protoplasm), which are not produced otherwise. Neither gravity nor life have as yet been brought under the control of man.

7. The sensory organs of man only respond to very small fractions of possible vibratory motions even when most highly developed, record much less when little trained or when undeveloped beyond the needs of his immediate necessities. Therefore, all individual judgment about the effect of any motion, force, or energy engendered is apt to be erroneous and at fault. Absolute truth or certainty in all or any given direction could only be attained by a being whose senses were atuned for correct impressions by all possible vibrations, and whose experience and knowledge were 80 comprehensive as to correlate them correctly, and therefore foresee all ultimate effects of changes effected by itself or by others. To such a

being everything conceivable would be possible. All possibility of doing wrong would be excluded-that is, of producing evil or harmful results for itself or nature at large, either directly or indirectly, and the results of its actions would be always as desired, and not, as in the case of man, turn out different through oversight of some factors. In this connection it must also be remembered that the high development of any one faculty or branch of knowledge does not and cannot compensate in judgment for the neglect of others, as all interact, and the deficiency of one must render the deductions from the others alone faulty. To this refer the truisms that "a little (viz., defective) knowledge is dangerous," and "angels fear to tread (hesitate) where fools rush in "-to perish.

8. All terrestrial life is the effect of solar energy, and of the stores of such laid up during past ages under well-known unalterable laws. Wherever these operate without undue interference by other agents or forces, fertility rules and progress ensues. This is generally understood when the expression "balance of nature " is used. When this is disturbed by man-consciously or unconsciously-or other forces, sterility or deterioration of fertility results, and the beneficent action of the sun's forces is suspended until favourable conditions are again slowly established.

9. Though mineral matter and solar energy are practically unlimited, the saved and preserved stock of the latter, laid up in the soil ready for the use of the higher forms of life, is more or less limited in most parts of the habitable part of the earth, and therefore exhaustible in periods proportionate to its quantity and the methods of removal employed, unless replenished in accordance with nature's methods. The knowledge or comprehension of these methods is by no means general.

In conclusion of these introductory remarks, the points to be borne in mind while studying any natural problem are briefly these:

1. Unity of nature.

2. Matter and motion the base of all phenomena of nature.

3. Inertia of matter.

4. Absolute matter not known or recognisable.

5. Matter in motion alone exhibits energy or force.

6. Life, as a form of motion, beyond the ken or control of man.

7. Imperfect and limited range of man's sensory organs, consequently fallibility of judgment (hence his actions are right or wrong in proportion to his range of understanding).

S. All life the result of solar energy (I do not say the "origin" of life) as applied according to certain laws.

9. Matter fit to support higher life is limited and exhaustible.

II. What are Trees?

Let us now enter into the consideration of the above question, in order to find out what their role in nature is.

If we propound the question to the "masses," or even a large proportion of the "classes," we may get for answers "raw timber," 66 uncut firewood," "dispensers of shade or shelter," "ornaments for gardens and parks," &c., &c. To the thinker, however, who is used to look beyond the surface, who devotes his life to the acquisition of understanding the modes and where

fores of existence, there is another definition, truer, though perhaps less apparent. It is this: Trees, in respect of life, are the principal mediators between sun and earth, inasmuch as they are the chief and most perfect savers of solar energy while living. They rank among the greatest marvels of organic nature while alive, and as long as they live and grow, as in that state they exhibit the most astounding display of mechanical forces. Every large tree raises, distributes, and causes to descend again hundreds of gal lons of water daily; every drop collected by its roots, combined with the mineral matters forming part of its nutriment, and a portion transformed into sap by the light of the sun, returned again to the tiniest rootlets for their sustenance and further development. Hidden under an apparently inactive surface, the unthinking perceive not that the simplicity and effectiveness of that action far transcends any human invention of similar purport or intention, viewing it as they do some crude manufactured article. In the larger species the durability of this living machine also exceeds everything ever constructed by man.

Trees are the "elect," the aristocrats of the vegetable world, and what man is in the animal kingdom. They are the most noble and the most effective by far of the links of life between sun and earth, mineral and man. Without abundance of them, notably when gathered in large communities (forests), most, if not all the countries of the earth must finally sink back into the state of more or less sterile deserts, as through their action during previous ages they first became fit abodes for man and his civilisations. The crowds of the humbler vegetation are merely pioneers or aiding dependents, just as the great majority of an army (the private soldiers) act as pioneers and aids to the staff of officers, and are powerless, except for evil, without their controlling forethought and direction. The idea that the sun supports human life by light and heat alone is wholly erroneous; the imparting to the soil the capacity of bearing fruit for his sustenance by means of the roots of trees and other woody plants is by far the more important, as by the loss of this capacity a country, or part of such, or even the whole earth, must become uninhabitable long before the supply of light and heat may fail.

When speaking of trees, not only the tall forms, the shade-dispensing, ornamental, or fruit-yielding are meant, but all more or less solid, deeprooted, perennial ones, usually called shrubs. Strictly speaking, trees are single-stemmed-shrubs several-stemmed woody plants; but as the former can be turned into shrubs by stunting the main trunk, and shrubs into trees by permitting only one of the branches to grow, the difference is only formal. In both there is a part whence growth proceeds in opposite directions, and forms the base. This in our " Mallees" is very short, irregular in form, and wholly subterranean. Representing the trunk, although popularly known as "root," it develops short branches above, and very long ones-the real roots-below. The latter exist in two sets, viz., one horizontal near the surface, the other more or less perpendicular and descending to great depths, in fact to the level of perpetual coolness and water supply. To this it is owing, that these wonderful dwarf forests can flourish in many large areas, where no others could possibly establish or maintain themselves under existing circumstances (viz., climate, and nature of subsoil). The fertility of the "mallee" soil is wholly due to the woody plants growing thereon; when once quite exhausted, no "science" will be able to re-establish it, as not even "mallee " roots will be able to pass through the depths of driedout and heated porous subsoil. The popular contempt for "mallee scrub" is, therefore, undeserved, and due to want of thought (reflection) and prejudice.

III.-How Sun-force is conserved and stored as fertility.

The life supporting solar energy is transmitted to the earth in the form of light and heat, and converted into organic substances by means of plants. As is well known, the green foliage absorbs carbonic acid from the atmosphere during daylight, appropriating the carbon, and setting the oxygen free. Within the leaves, and other parts containing chlorophyll cells, the carbon is combined with the mineral substances and the water into "sap," which is analogous to animal "blood," and contains all substances necessary for the building up of the plants in solution. But while all green plants do this, all the woody forms do it at a high rate, in a form not easily destroyed or removed by wind or weather, and all the year round. They also protect the humbler members and their products from destruction or dispersion by temporary excessive heat, wind, or floods.

Their roots ramify through the otherwise dead subsoil; the successive decay of the external layers forms a porous, cool wrapper around each, they thus form a network of filter-like channels, along which the water can descend and drain, and which also act as stores or reservoirs, where the soluble ingredients required for their food, and that of the humbler and more delicate members accumulates. When dead and decaying, their tissues change into carbonaceous mould or humus, representing plant-food in the exact proportions desired for absorption; that is, saved and stored solar energy. This appears to be the only means employed by nature in combination with low animal life to change gradually the dead mineral matter into the organised fertile soil necessary for abundant higher plant life, and yielding food for man and beast. When destroyed by burning-it matters not whether slowly by long-continued solar heat, or quickly by combustion-the solar vivifying energy saved and stored is wasted and dispersed, the organic soil reduced to dead mineral matter, and rendered sterile when the last carbonaceous particles have been withdrawn.

But the above is not the only way in which trees act beneficially. The foliage produces shade; that is, prevents a certain proportion of sunlight from reaching and heating the soil. It remains cooler than if not so shielded; less carbon (mould) is burnt up, much less of the water evaporated, and, therefore, so much stored sun-force or fertility saved. Bare ground not within the influence of rivers or springs soon loses all fertility, and becomes stony. The fallen leaves, fruits, twigs, &c., on the one hand, give shelter to worms and other low animal forms, which penetrate the ground, and carry with them to the subsoil the fertile compounds of the surface; and on the other, offer a formidable array of obstacles to the flow of the water yielded by the rain; the latter finds, therefore, abundant time and facilities to soak into the soil. We may, therefore, safely affirm that trees and shrubs not only store sufficient water for their own use in the seasons of drought, but also for the humbler plants and animals, nay, by supporting numerous small springs materially contribute to the habitability of many countries of the earth. The idea that trees and plants-no matter what they be-exhaust the soil is totally erroneous and false. That which exhausts is the continued removal of plants as fodder, grain, &c., or by burning, also the desiccation (washing out) of the bare ground by the water passing over or through it, and the burning of it by the rays of the sun. By dispersing the reflected light and heat rays in all directions by the leaves of trees and shrubs, the atmosphere above a wooded area is always cooler than over a bare or merely grass-grown one, the degree of reduction depending upon the size of the area and the density of foliage. This subject is, however, too wide for anything but the mere mentioning thereof.