Outlines of Creation

by Elisha Noyce

It was formerly supposed that the lowest grades of the animal kingdom were higher than the highest of the vegetable kingdom; this is not strictly true, the best way of viewing the connection between the two kingdoms is to approximate the lowest of each, when it will be found that our most acute physiologists are only just beginning to determine their distinctive characters.

Dr. Carpenter says:—"In the present state of science it would be very difficult, and is perhaps impossible, to lay down any definite line of demarcation between the two kingdoms, since there is no single character by which the animal or vegetable nature of any organism can be tested.

"Probably the one which is most generally applicable, among those lowest organisms which most closely approximate to one another, is not, as formerly supposed, the presence or absence of spontaneous motion, but the dependence of the being for nourishment upon organic compounds already formed, which it takes (in some way or other) into the interior of its body, or its possession of the power of obtaining its own alimentary matter by absorption from the inorganic elements on its exterior. The former is the characteristic of the animal kingdom as a whole, the latter is the attribute of the vegetable."

Both vegetables and animals begin with a simple nucleated cell, having certain vital properties, a double chain ascends from this simple type, one branch of which is developed more and more till it arrives at a perfect vegetable, and the other branch is developed till it arrives at a perfect animal. Thus, by the addition of distinctive and characteristic appendages, one being acquires properties regarded as vegetable, while by the addition of other appendages equally characteristic, the other being obtains those properties which cause it to rank as an animal; but it must not be inferred from this that all organic forms have been a simple cell at some former period, but that there are two classes of organic beings, the vegetable and the animal, and that each embraces forms, ranging from a simple cell to the highest, and that each of these forms (from the lowest to the highest) is and always was, from their first creation, the same as they now are, in individual shape and size. Some of the lower members of the animal kingdom resemble the higher members of the vegetable kingdom, both in outward appearance and in intimate structure; Dr. Darwin, who wrote scarce half-a-century ago, says that a tree should no more be considered as one plant than a branch of coral as one animal, for as it is found that in the coral hundreds of separate beings exist associated in one habitation, so (he says) should every bud on a tree be considered as a separate being. Even Dr. Carpenter, one of our most eminent physiologists, seems in a great measure to favour this idea. He says: "The radiata possess many points of affinity with the vegetable kingdom, and of these the circular arrangement of their parts is one of the most evident. Many species of sea-anemones, for instance, present an appearance so much resembling that of various composite flowers, as to have been commonly termed animal-flowers, a designation to which they seem further entitled from the small amount of sensibility they manifest, and the evident influence of light upon their opening and closing.

"But it is in the tendency to the production of compound fabrics, each containing a number of individuals, which have the power of existing independently, but which are to a certain degree connected with one another, that we recognise the greatest affinity in structure between this group and the vegetable kingdom. Every tree is made up of a large number of buds composed of leaves arranged round a common axis; each bud has the power of preserving its own life and reproducing the original structure when removed from the parent stem, if placed in circumstances favourable to its growth, and yet all are connected in the growing tree by a system of vessels which form a communication between them. This is precisely the nature of those structures which are formed by the animals of the class that may be regarded as the most characteristic of the group. Every mass of coral is the skeleton of a compound animal, consisting of a number of polypes, connected together by a soft flesh in which vessels are channelled out; the polypes are capable of existing separately, since each one, when removed from the rest, can in time produce a massive compound fabric like that of its parent, but they all contribute to the maintenance of the composite structure so long as they are in connection with it. In some instances the skeleton is stony, and is formed by the deposition of calcareous matter either in the centre of each fleshy column, so as to form a solid stem, or on its exterior so as to form a tube. In other cases it is horny, and then it may be a flexible axis in a delicate tube. Both the stony and horny corals often possess the form of plants or trees, and as their skeletons are often found with no obvious traces of the animals to which they belong, they have been accounted vegetable growths."

DESCRIPTION OF A VEGETABLE AND ITS PARTS.

As has been said before, it is extremely difficult to make any distinction between the lower tribes of the vegetable and animal kingdoms, and physiologists are not yet agreed, with respect to some members, as to which kingdom they belong. Their whole substance is made up of cellular tissue, and there are but few distinctions of parts, forming generally a broad foliaceous expansion called the "thallus," as in lichens and sea-weeds, or a sort of root composed of fibres and called the "mycelium," as in the fungi. But, a very few steps higher, the distinctive characters become so evident that they are impossible to be mistaken, the following description will therefore apply to vegetables of the more elevated character, such as trees or flowering plants.

Plants are fixed to the earth, and receive nourishment from it by imbibing its liquids, which circulating upwards through the porous structure of the plant itself, and becoming exposed to the air in the leaves, attract to themselves nourishment from that source also. The part of a plant which grows into the earth is called the root; this has a variety of forms, in some it is branched like the upper part, and these branches divide into rootlets or fibres penetrating deep into the ground, and absorbing nourishment in all directions, but this absorption does not take place from the whole surface of the root but from spots covering it, and from the slightly expanded ends of the fibres, these portions are formed of new and porous cellular tissue, and are called "spongioles." The part of plants which springs upwards from the earth is called the stem, if large the trunk, this divides into branches and twigs; stems in some cases continue for a distance more or less underground. The part of a potato plant, usually called the root, and from which the tubers or potatoes grow, is in reality an underground stem, and the fibres which spring from it are the roots; the underground suckers of mint are also portions of stem, and in some cases these are greatly expanded, they then obtain the names of "tubers" (as the potato), or "corm," as in the crocus and meadow saffron; when the stem is thin and runs along the ground, sending in roots at intervals (as in the strawberry), it is called a "runner," when thicker and running horizontally under the ground, it is called a "rhizome."

The stem consists of a central portion, either made up of long bundles of woody fibre running side by side, as in the endogenæ, or deposited in rings and having a central cylinder of pith, as in the exogenæ. In these the wood at the central part (or the oldest) is called "duramen," or "heart-wood," while that at the outer part or nearest to the bark (the newest), is called "alburnum" or "sap-wood." The former is the harder and the latter the softer portion. From the pith in the centre, through the woody part, rays or laminæ of cellular tissue similar to that which constitutes the pith itself, are sent outwards through the woody rings to the inner part of the bark, which they form; these are called medullary rays, and may be seen in wood which has been cut across the grain, they are often called the "silver grain," and are very evident in oak, beech, and elm, the inner part of the bark is called the "liber." The bark itself is made of cellular tissue dried and hardened by age; the outer portion (called the "epidermis") is in many cases shed, and may be constantly seen hanging loosely from the bark of the birch and other trees in loose white silvery portions. The outer part of the bark of some trees is so largely developed as to be of considerable thickness, this is especially the case in the Cork oak (Quercus suber), which is the cork of commerce. The bark cannot stretch as the circumference of the tree increases, it is therefore split up and cracked, which accounts for the rough state of it on those trees which do not shed the outer part.

The chief appendage of the branches, is called a leaf, it grows from a small projection called a leaf-bud, which contains the leaf rolled up. The method in which this occurs is different in different plants, in some it is folded backwards and forwards, in others doubled up with the opposite leaf alternately, and in various forms in other plants. The leaf consists of two parts, the stalk (petiole) and the blade (lamina); the blade is of different forms, and has ribs and veins covering it, in some of a reticulated or network pattern, these belong to the exogenæ, and in others running parallel, which is the kind of venation found in the leaves of the endogenæ. When leaves are placed on a stalk, they are said to be "petiolate," when without one, "sessile."