Outlines of Creation

by Elisha Noyce

"As we traverse a succession of lawns and open forests, it is interesting to observe something like instinct developed even in trees. One, which when cut emits a milky juice, and if met with on the open lawns grows as an ordinary umbrageous tree, and shows no disposition to be a climber, when growing in a forest still takes the same form, then sends out a climbing branch which twines round another tree until it rises 30 or 40 feet, or to the level of the other trees, and there it spreads out a second crown, where it can enjoy a fair share of the sun's rays. In parts of the forest still more dense than this, it assumes the form of a climber only, and at once avails itself of the assistance of a tall neighbour, by winding vigorously round it, without attempting to form a lower head. It does not succeed so well as parasites proper, but when forced to struggle for space, it may be mistaken for one which is invariably a climber."

FIG. 5.—PINE TREES ON MOUNTAIN SIDE.

FIG. 6.—SEED BEGINNING TO GROW.

The absence of heat with plenty of light is shown in the vegetation of mountainous districts, where there is great size, but the absence of leafy expansion, as in the pine tribe (fig. 5). Where both light and heat are deficient, nothing but fungi, mosses, and lichens of the most stunted nature will grow. Experiments in hothouses prove that although tropical plants be supplied with their proper amount of heat, yet without the very greatest supply of light that can be obtained, they do not come to any degree of perfection. The influence of light is chiefly upon the leaves, that of heat upon the earth and root, which becomes more fully developed. When a seed is placed in the earth, moisture is absorbed by it from the earth, and a development of the cells of the cellular tissue of which the seed is composed takes place, and from the peculiar nature of these cells they divide into two sets, one of which passes upwards towards the light, the other passes downwards into the earth; these last (which pass downwards) form a fibre called the "radicle" (fig. 6), those which pass upwards form also a stalk or fibre called the "plumule," which carries up with it a part of the seed called the "cotyledon," which (like a leaf) has the power of decomposing the carbonic acid of the air and fixing its carbon in the form of wood. This begins as soon as the cotyledon has reached the light, and thus the formation of fibres of woody matter takes place, which fibres descend from the cotyledon to the radicle. Meanwhile the formation of other cells of the plumule takes place, until the first leaf is formed, when other fibres of wood are sent down, and so on for every leaf, so that the number of woody fibres which form the trunk of a tree is in proportion to the number of leaves which that tree has borne, from which we come to the conclusion that the size of the trunk of a tree is the sum of all its branches. While all this is going on, the cellular tissue of the downward part or radicle also becomes developed and divides out into roots, on the surface and at the extremities of which are minute cellular bodies called "spongioles" (from their power of absorbing moisture), which take up the fluid of the earth which surrounds them; this moisture ascends through the vessels of the plant till it arrives at the surface of the leaves, where it is exposed to the action of light and sunshine. The ascent of the moisture of the earth was first correctly explained by Du Trochet, and is owing to a peculiar power which he discovered, and which is called "Endosmose;" this consists in the tendency which a fluid has to penetrate a membrane on the other side of which is a fluid of greater density than itself. This may be seen by the following experiment: obtain a piece of glass tubing about a foot long, having the end blown out into the form of a bell, as in fig. 7, tie a piece of bladder over the expanded end and fill it partly with syrup or gum-water, so that this shall rise in the stalk about an inch; place this in a glass of water with the bladder downwards, and the fluid will be seen slowly to rise in the stalk, so that in perhaps an hour it will rise to the top. This apparatus resembles one of the spongioles at the extremity of the fibre of a root.

FIG. 7.—ENDOSMOSE.

The rain falling through the air carries with it a certain amount of carbonic acid and ammonia, which the air always contains, and this is the whole source of the nitrogen which forms a very important part of the bodies of plants and animals. When the rain arrives at the surface of the earth, it sinks down into it and carries with it all soluble vegetable or animal matter which it meets with, together with any soluble earthy matter which may exist in the soil; this forms the sap of the tree. When it arrives at the surface of the leaf, the watery part of it combines with the carbonic acid of the air (through the influence of light) and appropriating its carbon, gives out the oxygen; this is the true respiration of plants, and is exactly the reverse of what takes place during the respiration of animals, in which case oxygen is absorbed and carbonic acid given off. The carbon thus retained by the plant combines with the elements of the water to form the solid green substance called chlorophyll, which is the basis of all the tissues of the plant, the ammonia is also decomposed, and its nitrogen combining with the oxygen and hydrogen of the water, and the carbon of the carbonic acid forms those compounds which constitute the most nourishing parts of vegetables, such as albumen, gluten, &c., and of which all the animal tissues are built up, for the production of these organic substances takes place in the vegetable only, animals simply appropriating them from their food. The sap which reaches the leaf is not all converted into chlorophyll, but also into those peculiar juices which are found in plants, some of which contain sugar, some gum, others (as the pine tribe) turpentine, and in the laurel tribe camphor, all of which are substances containing much carbon; moreover the solid wood and bark are deposited from these juices as they descend from the leaf after having been acted on by light (or the actinic power associated with it). Now, as the water, ammonia, and carbonic acid which descend with the rain are from the air, and as the vegetable is formed wholly by their absorption, it may be fairly said that the vegetable kingdom (and therefore the animal) feeds upon the air, and that the trees do not grow out of the earth but into it.

With respect to the position which the vegetable kingdom occupies in creation, there can be no doubt that it is subordinate to the animal kingdom, and takes a place between it and the mineral world, inasmuch as it prepares food from the one kingdom and transfers it to the higher. It has been supposed that the vegetable and animal kingdoms aid and support each other equally and mutually; this is true with respect to respiration, but not as regards nutrition, for although in the decomposition of animal matters, food is given off for the vegetable, yet they are quite independent of this source of nourishment. A forest of trees would be quite as well nourished if there were no animals, but on the other hand the animal kingdom would shortly cease to exist if there were no vegetables.