tles1 clustered so on some kinds of Mimosa, that the branches bent under the weight of their glittering burthen."

The same author mentions a curious distinction between the luminosity of the glow-worms and fire-flies in Brazil, which has been confirmed to me by a gentleman some time resident in that country. In the former, he says the light perpetually scintillates, but in the latter it is constant; the kind of glowworm most common in that part of America, belongs to a tribe in which the shield of the thorax does not cover the eyes, and the females is winged as well as the male. Thus in these little illuminators of tropical nights we have a kind of mimic stars and planets, the former of which are so numerous as to fill the air with their scintillations.

The immediate object of this faculty, in these beetles, and in other insects, has not been clearly ascertained; as the females are usually most luminous, it may be to allure the male; or, as most insects fly to the light, it may also bring their prey within their reach; or, again, it may be a defence from their own nocturnal enemies; but whatever be its object with respect to the animals themselves that are gifted with this faculty, they give man an opportunity of glorifying his Creator, not only for the starry heavens, but also for these little flying stars that render night so beautiful and so interesting, where they

occur.

In considering the great Class of Insects with reference to their office, the first thing that strikes us is their infinite number, not only of individuals of the same species, but of different species and even genera, and the vast variety of forms and structures that they necessary include. When we began the present subject, and, dipping under the waves of ocean, visited the vast world of waters, to survey their various inhabitants; even amongst those that can be seen only by the assisted eye, we saw no traces of such diversity; the number of individuals, it is true, were incalculable, but though they have been the objects of research, with so many inquirers, and for so long a period, the number of species known fall short of half a thousand, while the number of Insects already in cabinets are stated to be more than two hundred times that number, and

1 Entimus imperialis, and nobilis.

3 Ann. des Sc. Nat. xx. 247.

2 Ann. des Sc. Nat. xx. 161.

4 In the Introduction to Entomology. (ii. 407) this genus is named Pygolampis, after Aristotle, Hist. Anim. 1. iv. c. 1.

5 See above, p. 308.

even, in our own country, more than ten thousand have been enumerated and named.

The momentum of so vast a body of animals, everywhere dispersed, and daily and hourly at work in their several departments, must be incalculable; and this momentum must be doubled by the circumstance that so singularly distinguishes a large proportion of them; I mean that the different periods of their existence are passed under different forms, during which they have quite different functions assigned them, and are fitted with different organs, being, when they are first disclosed from the egg, masticators of solid and grosser food, and in their last state imbibing nectarious fluids. The connection of the first is with the leaves of the plant, to them they are committed by the mother as soon as they are extruded from her matrix, and they supply them with their earliest and latest food; but when she is disclosed in all her beauty, dressed as it were in her bridal robes, the connection is between her and the flower, her lovely analogue, from them she imbibes the sweet fluid which their nectaries furnish, and now, instead of a devourer, she abstracts merely what is redundant, which, while it contributes to her own enjoyment and support, in the case of the bee, enriches man himself.

We behold, then, this immense army of devourers, varying so infinitely in their instincts, as well as their forms, supplying many animals with the whole of their subsistence, and forming a considerable portion of that of others, and feel convinced that Providence has not placed them in their position, and given them such a variety of organs, except with the view to some great general benefit to those animals amongst whom he has placed them; and this benefit is not so much perhaps the reducing the numbers of their own class within due limits, though that is a most important object, as removing nuisances, which would deform, or in any way infect the earth and its inhabitants. For this the Insect world is principally distinguished as to its functions. It consists of the scavengers of the earth, and the pruners of its too luxuriant productions.

With respect to ornament and pleasurable sensations, which were certainly the object of our beneficent Creator, as well as our profit and utility-next to the birds, nothing adds more to the life of the scene before us, during the diurnal hours, and even sometimes the nocturnal, than the vast variety of insects that are flying, running, and jumping about in all directions, all engaged in their several pursuits,-the bees humming over the flowers; the butterflies opening and shutting their painted wings, to the sun; the gnats, and gnat-like flies, rising and

falling alternately in the sunbeams; the beetle wheeling his droning flight; others coursing over the ground; the grasshopper chirping in every bank-all adding to the general harmony, and combining to make the general picture one of life and Lova; and speaking, each in different sort and manner, the praises of its Creator, and calling upon man to join in the general hymn.

39

CHAPTER XXI.

Functions and Instincts. Fishes.

THE animals we have hitherto considered have been destitute of an internal jointed vertebral column, and its bony appendages; and though some, as the Cephalopods, and some slugs, have a kind of internal bone, and in one Order of Polypes the axis is sometimes articulated, yet these, especially in the latter instance, merely indicate an analogical relation, but no affinity. In none of these instances is this internal bone perforated for the passage of a spinal marrow, as in a real vertebrated column; we now, however, enter that superior section of the animal kingdom, the individuals belonging to which, with scarcely any exception, are built upon the column in question, incasing a spinal marrow, and terminated at its upper extremity by a bony casket, calculated to contain and protect the most precious and wonderful of all material substances, the cerebral pulp, by which the organs of sense perceive; the will moves the members; the mind governs the outward frame; and, in the king of animals, an immortal spirit, is enabled to seek and secure a higher destiny.

This change in the structure of animals was rendered necessary by an increase in their bulk; for though there are some of the invertebrated Sub-kingdom, as the fixed Polypes and several of the Cephalopods, that are of as large dimensions, and a few of the vertebrated, as the humming birds, and the harvest mouse, that are not so large as some insects; yet the generality of those distinguished by a vertebral column form a striking contrast, as to magnitude, with those that are not. Besides this, as these animals, by the will of their Creator,were to be endowed as they ascended in the scale, with gradually increasing intellectual faculties, it was necessary that the prin cipal seat of those faculties should be differently organized. A different organ of respiration also, as well as of circulation, in the

1 See above, p. 164.

3

Trochilus.

2 Ibid. p. 94.
4 Mus messorius.

great body of vertebrates, required an internal cavity defended from the effects of pressure.

Having premised these general observations, we are next to consider what animals form the basis of the vetebrated Subkingdom. Most modern zoologists appear to be of opinion that the Fishes occupy this position, and, taking all circumstances into consideration, this seems the station assigned to them by their Creator; still there are characters in some of the Reptiles, that seem to connect them more immediately with the Insects. The metamorphosis, particularly of the Batrachian Order, are of this description; as is likewise the carapace, or shell of the Chelonians, of which the vertebral column and ribs form the basis. Those extraordinary animals, the hag1 and the lamprey, half worms and half fish, by means of the leech, evidently connect the Fishes with the Annelidans. Perhaps those butterflies of the ocean, the flying fishes, with their painted wing-fins with branching rays, may look towards the Lepidoptera amongst Insects, but there is no direct connection at present discovered between the two Classes.

The characters of the Class of Fishes are-Body with a vertebral column, covered with scales, and moved by fins. Respiration by permanent gills. Heart with only one auricle and one ventricle; blood red, cold.

Fishes are distinguished from the other vertebrated animals, especially birds and beasts, by their mode of respiration; the latter breathing the atmospheric air, are furnished with lungs, which receive that element, oxygenate the blood, and again expel it in a different state; while the former, which must decompose the water for respiration, breathe by means of gills, found also in many invertebrates; these are usually long, pointed plates, disposed like the plumules of a feather, or teeth of a comb, in fishes attached to bony or cartilaginous bows; each of them, according to Cuvier, covered by a tissue of innumerable blood-vessels; but, according to Dr. Virey, having a minute vein and artery. In the gill of a cod-fish, which I have just examined under a microscope, a vein and artery traverse each plate longitudinally at the margin, which appear to be pectinated, at right angles on each side, with innumerable minute branches, and resemble, in this respect, the gills of Crustaceans. Thus the blood is oxygenated by the air mixed

1 Gastrobranchus. (Myrine. L.)

3 Sir E. Home, Philos. Trans. 1815, 265. 5 N. D. D'H. N. iv. 330.

6 Latr.

2 Pteromyzon.

4 Exocatus volitans, &c. Cours. D'Eut. t. 2. f. 2.