and peculiar, in different species, with regard to matters of subordinate detail. In all the more perfect animals, reproduction takes place by means of a seed or ovum, which is a process essentially different in its nature, as well as in the mode of operation, from those already described. In the animal as well as vegetable world, the germ latent in the seed is never developed, beyond a certain point, unless it be vivified by the action of a peculiar fluid belonging to other organs. The germ, when thus impregnated, receives the name of embryo, and the development takes place in one or other of the four following ways:—

1st, The ovum, when defended by a firm envelope, which contains a store of nutriment, is termed an egg, and is deposited in situations most favourable for the development of the embryo, and also for its future support, when it emerges from the egg. Birds, as is well known, produce eggs which are encased in a calcareous shell, and hatch them by the warmth they communicate, in sitting on them with unwearied constancy. All animals which thus lay eggs are termed oviparous.

2d, There are a few tribes, such as the viper and the salamander, whose eggs are never laid, but are hatched in the interior of the parent, so that they bring forth living offspring, although originally contained in eggs. Such animals are said to be ovo-viviparous. There are other tribes, again, which, according to circumstances, are either oviparous or ovo-viviparous. This is the case with the shark.

3d, Viviparous animals, are those in which no egg, properly so called, is completed; but the ovum, after passing through the oviduct, sends out vessels which form an attachment to the interior of a cavity in the body of the parent, whence it draws nourishment, and therefore has attained a considerable size at the time of its birth.

4th, Marsupial animals, are those which, like the kangaroo and the opossum, are provided with abdominal

pouches, into which the young, born at a very early age of development, are received, and where they are nourished with milk secreted from glands contained within these pouches. As the young, both in this and the last case, are nourished with milk prepared by similar glands, or mamma, the whole class of viviparous and marsupial animals has received, from this characteristic circumstance, the name of Mammalia, that is, animals with teats, or milk-vessels.*

The varieties now mentioned in the means, by which the first processes of reproduction are effected, are neither accidental nor capricious. They are adaptations of remarkable wisdom, connected always with peculiar conditions, either in the state or structure of the organized beings in which they occur. They are parts of a system, which is perfect in its various functions and relations, and admirably suited to fulfil the object in view. We may not always be able to trace the peculiar bearings of this system in all its branches; but, in general, it is open, at least in its great features, to human research, and, even where it is more recondite, there are still circumstances of obvious adjustment, which enable us confidently to say, that here are indications of admirable contrivance and forethought. The simple mode of reproduction, for example, by partition or fissiparous generation, as it is called, or even by buds or germs, produced externally or internally, though well adapted to animals of the infusory tribes, would obviously interfere most essentially with the active functions necessary for the preservation, defence, or enjoyment of animals of a higher grade, and inhabiting another element. We have only to conceive a bird, a quadruped, or a human being, constantly, or even occasionally, undergoing either of the remarkable processes by which a monad or a zoophyte multiplies its species, to perceive how unsuitable such a mode would be to their condition; and the more we compare the actual means employed, with the relative * Roget's Bridgewater Treatise, vol. ii. pp. 597-8.

VOL. II.

H

situation and circumstances of the different orders, the more reason shall we find to adore the perfections of the Creator. In this general statement, every person even on the slightest consideration, must find cause to acquiesce; and the more we enter into detail, our admiration will be proportionally increased. It is but a small portion, however, after all, that we can perceive of Creative Intelligence; because our ignorance continually interferes with the researches we make in any direction. All is full of wise adaptation and contrivance, so far as we can trace, and every new discovery of the properties and relations of things, affords us a further insight into the beautiful designs of an all-pervading mind; while the farther we penetrate, our convictions become the stronger that we are yet but at the surface, and that what remains behind, could we but dive still deeper, would only furnish us with more irrefragable evidence of the attributes we love and venerate, in what we actually behold. In prosecuting this pleasing subject, this view has constantly forced itself on my mind, and I have felt, that, while the operations I described have displayed much of the Divine power, and wisdom, and goodness, I was, after all, only taking an ignorant and superficial survey of a subject of infinite extent,-only looking at the elegant external proportions, and the outward grace of a building, which within was full of a fitness and a grandeur, that in this mortal state, with my limited faculties and imperfect knowledge, I was not permitted either to approach or to conceive. How delightful is the assurance, that the time will come when, if we belong to that blessed company who inherit the promises of the Gospel, we shall no longer see as through a glass darkly.” When that which is perfect is come, and we see 66 face to face," the further discoveries which our enlarged faculties shall be permitted to make, will, as we may well believe, form no mean part of the happiness which Heaven has in store for us.

66

FOURTH WEEK-THURSDAY.

INSTINCTS CONNECTED WITH THE REPRODUCTION OF ANIMALS.

HOWEVER curious and instructive the subject of reproduction may be, in relation to its physiological laws and conditions, it is certainly not less so as regards the instinctive propensities and habits, by which these are brought into operation and rendered effectual for the accomplishment of the great object the Creator had obviously in view; and there are few things more wonderful, or more strikingly indicative of wise and harmonious design, than the adaptation of the animal instincts to the physical circumstances of the parent, the embryo, and the offspring. Were there not an exact and intimate correspondence between those two distinct and totally dissimilar things, the material organization and the living propensity, reproduction would be impeded not only at every step of its progress, but at its very source, so that the continued existence of any one species of animals would be impossible. To enter into details as to some of these adaptations, would be as inexpedient as it is unnecessary; but the fact, that immediately after the wintry blast which desolated Nature has ceased, and as soon as Spring has begun to scatter a profusion of food over the face of the earth, and to cheer and nourish all things with her balmy breath, the lower animals should choose their mates, and those remarkable instincts should commence their influence, which are to repair the waste occasioned by the law of universal decay, and constantly to replenish the world with living beings, is, in all its circumstances, a phenomenon which clearly indicates the plan of an Intelligent Creator.

When from this general view we turn to the operation of these instincts in the various races of the animated world, we find with admiration and delight the same

uniformity mingled with diversity, which distinguishes the operations of the Creator in other departments of his works, the same adjustment of causes to ends, of instincts to forms, of propensities to propensities, and of one condition to all the rest.

I shall at present take a rapid view of these reproductive instincts, as they appear in the various tribes of animals, with the intention of afterward filling up the sketch by such details as may serve more fully to illustrate the Divine perfections, exhibited in the means made use of for the preservation of animal life through successive generations.

To begin with the insect world; these have all their seasons for fulfilling the great law of Nature, varying according to their peculiar functions and destinies, numerous as these are, to which the organization of each is most admirably adapted, and with which their reproductive propensities are in beautiful unison. It is exceedingly remarkable, as we shall presently see, to observe how each is directed to deposit its eggs where its young, when disclosed, may find their appropriate nutriment. Various circumstances seem to point to the scent,* as the sense by which they are directed to the proper station for their eggs. But whatever there may be in this, the inward propensity is not the less admirable, which conducts by far the most numerous classes of insects, and more especially the whole tribes of the Lepidoptera, to seek for a place of deposit for their precious charge, where their larvæ, when developed, may find a species of food suitable for the offspring, but never once used by the parents.

Of vertebrated animals, the lowest classes are coldblooded, including reptiles and fishes. These seem to have none of that instinctive regard to their offspring, which belongs to many of the former order, and is not

* The flesh-fly, deceived by the smell, frequently lays her eggs on the carrion plant, mistaking it for a piece of decaying flesh, which it greatly resembles in its disagreeable odour.