ZOOPHYTES.
"Nature is nowhere more perfect than in her smaller works."
"Natura nusquam magis quàm in minimis tota est." Pliny.
It will not be out of place here to offer some remarks on animals in general, including the whole kingdom as well as the great divisions which form the subject of this particular volume. But considering the vastness of the subject, and our imperfect knowledge of the whole animal series as a subject of study, nothing is more difficult than to seize upon the real analogies between beings of types so varied,—of organizations so dissimilar. The arrangements which naturalists have established in order to study and describe animals—the divisions, classes, orders, families, genera, and species—are admirable contrivances for facilitating the study of creatures numerous as the sands of the sea shore. Without this precious means of logical distribution, the individual mind would recoil before the task of describing the innumerable phalanges of contemporary animal life. But the reader must never forget that these methodical divisions are pure fictions, due to human invention: they form no part of nature; for has not Linnæus told us that nature makes no leaps, natura non facit saltus? Nature passes in a manner almost insensibly from one stage of organization to another, altogether irrespective of human systems.
Moreover, when we come to watch the confines of the animal and vegetable kingdom, we realise how difficult it is to seize the precise line of demarcation which separates the great kingdoms of Nature. We have seen in the "Vegetable World" germs of the simplest organization, as in the Cryptogamia, spores, as in the Algæ, and fruitful corpuscles, as in the Mosses, which seem to be invested with some of the characteristics of animal life, for they appear to be gifted with organs of locomotion, namely, vibratile cilia, by means of which they execute movements which are to all appearance quite voluntary. Side by side with these are vegetable germs and fecundating corpuscles, known as antherozoides among the Algæ, Mosses, and Ferns, which, when floating in water, go and come like the inferior animals, seeking to penetrate into cavities, withdrawing themselves, returning again, and again introducing themselves, and exhibiting all the signs of an apparent effort. Let us compare the Infusoria, or even the Polypi and Gorgons, with these shifting vegetable organisms, and say if it is easy to determine, without considerable study, which is the plant and which the animal. The precise line of demarcation which it is so desirable to establish between the two kingdoms of Nature is indeed difficult to trace.
The word zoophyte, to which this comparison introduces us, seems very happily applied: it is derived from the Greek word ζῶον, animal, and φυτὸν, plant; and is, as it seems to us, quite worthy of being retained in Science, because it consecrates and materialises, so to speak, a sort of fusion between the two kingdoms of Nature at their confines. Let us guard ourselves, however, from carrying this idea too far, and, upon the faith of a happy word, altering altogether the true relations of created beings. In adopting the name zoophyte, to indicate a great division of the animal kingdom, the reader must not imagine that there is any ambiguity about the creatures designated, or that they belong at once to both kingdoms, or that they might be ranged indifferently in the one or the other. Zoophytes are animals, and nothing but animals; the justification for using a designation which signifies animal-plant is, that many of them have an exterior resemblance to plants; that they divide themselves by offshoots, as some plants do, and are sometimes crowned with organs tinted with lively colours, like some flowers.
This analogy between plants and zoophytes is nowhere more apparent than in the coral. Rooted in the soil and upon rocks, the form of its branches many times subdivided, above all, the coloured appendages which at certain periods so closely resemble the corolla of a flower, have all the form and appearance of plants. Until the eighteenth century most naturalists classed the coral as Linnæus did, without the least hesitation, with analogous creations in the vegetable world. Réaumur long contended for the contrary opinion; but it is only in our day that the animal nature of the coral is satisfactorily established. The sea anemone may be cited as another striking example of the resemblance borne by certain inferior organisms to vegetables. We hold, then, that we are justified in using the word zoophyte to designate the beings which now occupy our attention.
We shall not surprise our readers by telling them that the structure of the zoophyte, especially in its inferior orders, is excessively simple. They are the first steps in the scale of animal life, and in them a purely rudimentary organization was to be expected. In these beings—true types of animal life—the several parts of the body, in place of being disposed in pairs on each side of its longitudinal plane, as occurs in animals of a higher organization, are found to radiate habitually round an axis or central point, and this whether in its adult or juvenile state. Zoophytes have not generally an articulate skeleton, either exterior or interior, and their nervous system, where it exists, is very slightly developed. The organs of the senses, other than those of touch, are altogether absent in the greater part of beings which belong to this, the lowest class of the last division of the animal kingdom.
Several questions arise here: Has the zoophyte sentiment, feeling, perception? Has it consciousness, sense, sensibility? The question is insoluble; it is an abyss of obscurity. The coral, or rather the aggregation of living beings which bear the name, are attached to the rock which has seen their birth, and which will witness their death: the infusoria, of microscopic dimensions, which revolve perpetually in a circle infinitesimally small; the Amœbæ, the marvellous Proteus, which in the space of a minute changes its form a hundred times under theœ surprised eyes of the observer, are, in truth, mere atoms charged with life. Yet all these beings have an existence to appearance purely vegetative. In their obscure and blind impulse, have they consciousness or instinct? Do they know what takes place at the three-thousandth part of an inch from their microscopic bodies? To the Creator alone does the knowledge of this mystery belong.
It would be foreign to the object of this work to enter into minute division of the innumerable creatures which swarm on the ocean and on its confines. We shall perhaps best consult the convenience of our readers by adopting the following simple arrangement of these animals into