Now, where shall we find it? In the first pair of developed leaves? They certainly point back to the cotyledons. To the cotyledons, then, let us look.
Lo! the young plant is germinating before its connexion with the parent is severed. It is the singular habit of this tree, that its seeds are already in a growing condition, while they hang from the twig. Each seed is a long club-shaped body, with a bulbous base and a slender point, more or less produced. While it yet hangs from the branch, the radicle and crown of the root begin to grow, and gradually lengthen, until the tip reaches the soil, which it penetrates and thus roots itself; while those which depend from the higher branches, after growing for a while, drop, and, sticking in the mud, throw out roots from one end, and leaves from the other.
SEED OF MANGROVE.
What have you gained, then, in this case, by going back to the germ? The germ as decisively asserts its origination from an already existing organism—the parent tree—as the flourishing tree witnesses its gradual development from a germ. The Mangrove could not by possibility have been created in any stage, consistent with the identity of the species with that which we behold now in the nineteenth century,—that did not show ocular evidence of a previous history;—evidence from the nature of things fallacious.
It would be merely tiresome to go on through the vegetable kingdom. In every plant the simplest condition—viz. that of a spore or seed—depends on some development, or process, or series of processes, that have preceded it. Nor does the lapse of time between the previous process and the apparent result at all destroy their necessary connexion. In the case of the curious Misseltoes, the ovule does not appear till three months after the pollen has been shed; but when it does appear, its existence as an organism capable of developing the characteristic form of its species, is as truly dependent on the previous existence of the pollen, as if not an hour had intervened.
Supposing the essential conditions of vegetable organisms to have been at the first what they are now; in other words, supposing specific identity to have been always maintained,—which I have demanded as a postulate for this argument,—it appears to me demonstrable, that every plant in the world presented at the moment of its creation evidences prochronic development, in nowise to be distinguished from those on which we firmly rely as proving the lapse of time.
But is the case otherwise in the animal world?
We traced back the history of our Medusa through its marvellous series of gemmative developments, till we reached the minute Infusory-like gemmule, which is its simplest form. Now it is quite legitimate to assume that this, and not the pulmonigrade umbrelliform stage, was the one in which the new-created Medusa began existence. Have we, then, got rid of the evidence of past time, which we deduced from the successive changes through which the adult had passed? What is this ciliated planule, and whence comes it? It is the embryo discharged from the fringed ovary of a female Medusa; it has already passed through several changes of colour and form. It is now of a deep yellow colour; it has been violet; it has been colourless: it is now shaped like a dumb-bell; it was a globule; it had been a mulberry-mass. Yet earlier, it had been a component cell of the ovarian band, which divided the generative cavity from that of the stomach, in the parent Medusa.