Origin of Species Variorum

condition will generally have been supplanted .. by their successors with the same organ in a more perfect and developed condition, and consequently will not now exist. The wing of the penguin is of high service, acting as a fin; it may, therefore, represent the nascent state of the wing; .. not that I believe this to be the case; it is more probably a reduced organ, modified for a new function: the wing of the Apteryx, on the other hand, is quite useless, and is truly rudimentary. The simple filamentary limbs of the Lepidosiren apparently are in a nascent state; for, as Owen has recently remarked, they are the "beginnings of organs which attain full functional development in higher vertebrates." ↑ The mammary glands of the Ornithorhynchus may, probably, be considered, in comparison with those of the cow, as in a nascent condition. The ovigerous frena of certain cirripedes, which are only slightly developed and which have ceased to give attachment to the ova, are nascent branchiæ. Rudimentary organs in the individuals of the same species are very liable to vary in degree of development and in other respects. Moreover, in closely allied species, the degree to which the same organ has been rendered rudimentary occasionally differs much. This latter fact is well exemplified in the state of the wings of female moths in certain groups. Rudimentary organs may be utterly aborted; and this implies, that we find in an animal or plant no trace of an organ, which analogy would lead us to expect to find, and which is occasionally found in monstrous individuals of the species. Thus in some Scrophulariaceæ we rarely find even a rudiment of a fifth stamen; but this may sometimes be seen plainly or fully developed. In tracing the homologies of the same part in different mem- bers