ORIGIN, or the acts by which species are con tinued.—Vegetables and animals alike derive their origin from a birth or genesis accom plished in two different modes, either without the concurrence of opposite sexes, or with such a concurrence. When organized beings are pro-• duced without the concurrence of opposite sexes, the parent either divides into several pieces, each of which becomes an independent individual, or throws out burgeons or buds from its surface, which, being detached in due season exist as self-sufficing types of the spe cies. When organized beings spring from the concurrence of sexes, again, two sets of organs minister to the generation, the one denominated male, supplying a fecundating matter, the other entitled female, furnishing a germ, which sub sequently to its impregnation by the male organ undergoes a series of evolutions that end in the issue of an individual resembling the parents, and fitted by its own acts to preserve itself and to continue its kind.
Both of these modes of reproduction are common to vegetables and animals.. Confervx and polypi alike exhibit the first mode, almost without a difference : • buds or sprouts arise from the surface of both ; these adhere for a time, acquire a certain size, and are finally detached to become independent beings. Again, the polype divided into several pieces, gives origin in each of these parts to distinct polypi, exactly as the cuttings of vegetables take root and grow into perfect trees, shrubs, &c.
The second mode of reproduction—that by the concurrence of sexes, or of organs deno minated respectively male and female,—is also exhibited by vegetables and animaV3 indiffer ently; but there are numerous circumstances distinguishing this manner of reproduction in the two classes of organized beings. In the first place, the sexual organs do not exist from the earliest period, and during the whole course of the life of vegetables, as they do in animals ; the sexual organs, in fact, only occur among vegetables at the time of flowering, and perish whenever the end of their evolution has been accomplished, never serving oftener than once for the generative act. The sexual organs of all animals, again, that live for more than a year, suffice repeatedly for their office ; and if they are not required to accomplish this oftener than once in the short-lived tribes, it is probably from no inherent incapacity to serve again, or any destruction of the organs them selves, but simply because the term of existence of the organism of which they formed a part is complete,--they perish with the system to which they belonged.
Another grand though not an invariable dis tinction between vegetables and animals is the mode in which the sexes, or sexual organs—for these may be taken as synonymous terms—are distributed among the individuals of each class.
Speaking generally, it may be said that the sexual organs are as commonly divided be tween two individuals among animals by whom the species is represented, as they are confided to one among vegetables, which is, therefore, singly the type of its kind. In both classes, indeed, there are exceptions to this general law : the flowers of all vegetables do not contain stamina and pistilla, or male and female organs, neither are the opposite sexes invariably repre sented by two different individuals among animals. In many plants the male organs are known to exist in one flower, the female in another, but both developed on the same branch ; in many others, again, they exist on dif ferent stems, and are often evolved widely apart from one another. In the same manner, many of the lower tribes of animals include within their individual organisms male and female organs ; this is the case with several tribes of the genus mollusca, gasteropoda, the helix, limax, and lepas, for instance, with the whole of the extensive classes of the annelida, en tozoa, echinodermata, &c.
But though there be resemblance to this extent among vegetables and animals in regard to organs, in.. the act by which fecundation is accomplished there is a wide and essential difference ; for whilst vegetables impregnate themselves, or, rather, whilst the impregnation of vegetables is a purely passive process, with out perception of or concurrence in its accom plishment on their parts,—the pollen of the anthers of those flowers that have male and female organs being simply shed upon the pistilla, the impregnation of animals, so far as our knowledge goes, appears to be almost as generally a consequence of a connexion be tween two different individuals, and of volition with consciousness on their several parts. Although many animals have both male and female parts included within the same organism, it would seem that comparatively few have the power of impregnating themselves : two in dividuals of the like species meet, and give and take reciprocally ; so that there is, in fact, much less difference between the highest and the lowest tribes of the animal kingdom in the essentials by which races are continued, than at first sight appears, much less certainly than there is between the vegetables and animals that are most nearly allied. The modes in which fecundation takes place in vegetables at large, and in animals probably without exception, are inherently and essentially distinct : an her maphrodite animal is still a very different thing from an hermaphrodite flower.