CHAPTER VI.

Functions and Instincts. Radiaries.

It happens not seldom to the student of the works of creation, when he is endeavouring to thread the labyrinth of forms in any of the three kingdoms of nature, and has arrived at any given point, to feel doubtful which course to pursue. The road divides, perhaps, into two branches, which both promise to lead him right. At the very outset of the animal kingdom, as we have seen, there was some uncertainty, whether we should begin by the Infusories or Polypes, and now the Tunicaries, or Ascidians as some call them, at the first blush seem more closeby connected with the Polypes, than the Radiaries, which Lamarck has placed next to them; but when we consider that the organization is much more advanced in the former than in the latter, not only in the organs of digestion, but in those of sensation, respiration, and circulation, we feel satisfied that the latter, where the object is to ascend, should first be considered. I shall, therefore, now give some account of the Radiaries.

The animals forming this class receive this appellation, because they exhibit a disposition to form rays, both in their internal and external parts, a disposition which begins to show itself, as we have seen, both in the polypes and the infusories* with respect to their oral appendages, and is found also in the tunicaries and cephalopods, or cuttle-fish. And this tendency in the works of the Creator to produce or imitate radiation, does not begin in the animal kingdom; the Geologist detects it in the mineral, and the Botanist in the vegetable, for Actinolites, Pyrites, and other substances exhibit it in the former, and a great variety of the blossoms of plants in the latter. We may ascend higher, and say that irradiation is the beginning of all life, from the seed in the earth and the punctum saliens in the egg, to the foetus in the womb; and still higher in the physical world, sound radiates, light radiates, heat radiates. If we farther survey the whole universe, what do we behold but

1 See above, p. 82, 89, &c.

radiating bodies dispersed in every direction. Suns of innumerable systems, shedding their rays upon their attendant planets; and the Great Spiritual Sun of the universe, even God himself, is described in Holy Scripture as that awful Being, "Whose goings forth have been from of old, from everlasting."

Cuvier, and after him several other modern Zoologists, have considered Lamarck's Class of Radiaries as forming a group or class of the zoophytes; but when we recollect that they cannot, like the infusories and polypes, be propagated by cuttings and offsetts, this seems to indicate an animal substance in which the nervous molecules are less dispersed, and that some tendency to nervous centres has been established. In the upper classes of invertebrated animals, indeed, many will reproduce an organ when mutilated, and some even a head, but none but the polypes and infusories multiply themselves in the way above stated. It seems, therefore, most advisable to adhere to Lamarck's system, by considering the animals in question, as forming a group by themselves, and to adopt his name of Radiaries.

These are distinguished from the class immediately preceding the polypes, by being limited as to their growth to a certain standard, as to their form by the general appearance of radiation they usually present, being either divided into rays, as in the star-fish; or having rays exhibited by their crust as in the sea-urchins; or embedded in their substance, forming appendages to their viscera, as in the sea-nettle or jelly-fish. They have not, like the polypes, a terminal mouth or orifice surrounded by food-collecting tentacles; but one placed, most commonly, underneath their body. Their digestive organs are distinct and more complex. They are never fixed, and are to be met with only in the sea and its estuaries. Lamarck has divided this class into two orders, the Gelatines' and the Echinoderms.

1. The Gelatines, which sotne consider as a distinct class under the name of Acalephes,3 are distinguished by a gelatinous body, and a soft and transparent skin; they have no retractile tubes issuing from the body; no anal passage; no hard parts in the mouth; and they have no interior cavity, their viscera being embedded in their gelatinous substance.

Some genera in this Order, like the fishes, are remarkable for an air-vessel which they can fill or empty, and so rise to the surface, or sink to the bottom at their pleasure, but it dif

1 Radiares molasses.
3 Acalepha.

2 R. Echinodermes. 4 Physsophora, &c.

fers from that of the fishes in being external; others are distinguished by a dorsal crest, which they erect and use as a sail.1

2. The Echinoderms have an opaque, leathery, or crustaceous skin, mostly covered with tubercles, or even moveable spines, and generally pierced with holes, disposed in rows; retractile tubes which respire the water, and are used also for locomotion and prehension, emerge from these holes; a mouth generally situated below, and armed with hard parts; and a cavity simple or divided.

To begin with the Gelatines-in walking upon the sea-shore, I have occasionally remarked an animal of this tribe left by the waves, not much larger than a nutmeg, of a spherical form, with several longitudinal ridges, and nearly as transparent as the purest crystal. If at all injured by the touch, it immediately dissolved. Such delicate creatures has the Creator exposed to the action of the oceanic waves, and they sail gaily on, by means of their ciliated tails, receiving no injury, frail as they are, except in being sometimes cast upon the shore. These lucid gems of the waters, which abound equally within the polar circle and near the equator, are eminently phosphoric. Bosc says, he has seen millions, which he could scarcely distinguish during the day from the water in which they lived, but which in warm and calm nights afforded the most brilliant spectacle. From their rotatory motion, they seemed then globes of fire which rolled upon the surface of the water. The more rapid their motion, the more intense the light, and their tails always emitted more than their body. They doubtless absorb animalcules with the water that they inspire, and they swim by a motion combining rotation with contraction and dilatation. They are found from a line to six inches in diameter. Providence has destined them to be the food of a vast number of fishes, even the whale does not disdain them; and we may conjecture the havoc that one of these giants of the ocean would make in their ranks. The manner in which they are propagated has not been ascertained, but from their infinite numbers in every sea, their progeny must be inconceivable. Another phosphoric animal of the present tribe is distinguished by a dorsal crest, resembling a vesicle full of air, and which it is said to use as a sail, like many of the Molluscans, to conduct it over the surface of the waves. It is connected

1 Vellela.

2 Beroe.

with the body only by its middle, its extremities being at liberty, which enables the animal to steer its course in any direction.

I shall mention one more of these gelatines, which falls under the observation of every one who is fond of sailing, or rowing, in a boat on the ocean or in its estuaries. If he cast his eye upon the water in fair weather, he will see numbers of animals, in shape resembling an expanded umbrella, with some fleshcoloured organs round the summit or centre, carried with the rising or falling tide, and dancing along with a seemingly undulating motion: these belong to what are vulgarly called the jelly-fish, or sea-nettles. Though the body of the animals of this tribe is gelatinous and easily melts, yet its weight is considerable, and it is said that they can render themselves heavy or light at pleasure, which some effect by means of a natatory vesicle, but the means in all has not been ascertained; unless they were thus gifted, as their specific gravity exceeds that of the water, they could not raise themselves to the surface, where they are seen swimming very gracefully; as it were, by an alternate systole and diastole, admitting and rejecting the sea-water. Several of them, for it is not common to them all, when touched, cause a sensation similar to that produced by the sting of a nettle:3 it is supposed by some that this is done by their tentacles, which are conjectured to have little suckers, as indeed is very probable, which adhere to the skin. This faculty, which is supposed to be the lowest degree of the electric power peculiar to several fishes, is found in other genera of this tribe; for instance, the Jamaica sea-nettle, is said to affect the hands, when touched, still more severely. Probably this faculty was given to them by Providence, either for the defence of their frail forms against their assailants, or to enable them to secure their prey, this being the general use of their numerous tentacles and other organs. Lamarck observes, that some of these animals are so large as to be more than a foot in diameter, and that some weigh as much as sixty pounds. Their multitudes are prodigious, and, as well as the beroe, they are said to form part of the food of the whale: they are even devoured by some of their own class. The mode by which these creatures are produced in such infinite profusion is at present unknown. They do not reproduce mutilated parts; therefore it cannot be, as in the polypes, by the division of their bodies.

1 PLATE III. FIG. 1.

2 Rhizostoma. Cuv. Cephe Rhizostomæ, Lam. 3 See Appendix, note 22.

4 Physalis pelagica

When we consider the extreme fragility and deliquescent nature of the animals constituting this order of the Radiaries, that a touch almost disorganizes their structure, and moreover that they form part of the food of the most gigantic animals in creation, we should be led to think it impossible that they could withstand all these combined actions upon them, and that however numerous and prolific, they must at length be utterly annihilated. Nothing less, indeed, than Almighty Power, and Infinite Wisdom and prescience, and a Goodness that is interested in the welfare of the meanest as well as the mightiest of the animals he has brought into being, could have preserved them from such a fate. He who made all things decreed their mutual relations, limited their numbers by certain laws, and appointed the means by which those laws should be executed. We may say, that in some sense the whales were created for the gelatinous radiaries and numberless other animals with which the seas frequented by these monsters abound, and that these gelatinous radiaries were created for the whales. The enormous mouth of the last-named animals is not armed with tusks or grinders, but fitted instead with vast numbers of oblique lamina of a softer substance, usually denominated whalebone, which is adapted only for the crushing and masticating of soft bodies; therefore instead of a prey more propor tioned to their bulk, they contentedly make their meal off these small but innumerable gelatines, which by their number, make up for their want of magnitude, and are exactly suited to the masticating organs of their devourer; and though the waste of animal life seems almost infinite, yet was it not for this check, so great appear to be the powers of multiplication of the smaller creatures that swarm under the ice of the Arctic seas, there would be more than could be maintained consistently with the general welfare.

The object of Providence throughout our globe, as has been before observed, is so to balance the respective numbers of the different kinds of animals, from the invisible monad to the gigantic whale, that a certain proportion may be preserved, with regard to their numbers, between them, so that each may be in sufficient force to accomplish the end for which it was created. We may observe that though the whale devours myriads of millions, yet the quantum of suffering is less than if he were enabled to make his meal off larger animals, and his jaws, like the shark's, were fitted with laniary teeth. In fact the gelatines are incapable of suffering pain, having no digested nervous system, and when cast upon the shore they dissolve into a fluid exactly resembling sea water.