Origin of Species Variorum

Comparison with 1866

effected somewhat abruptly by a few stages and in a concealed manner; but the transformations are in reality numerous and graduated. For instance, Sir J. Lubbock has recently shown that a certain ephemerous insect (Chlöeon) during its development moults above twenty times, and each time undergoes a certain amount of change; in such cases we probably behold the act of metamorphosis in its natural or primary progress. ↑ What great changes of structure are effected during the development of some animals is seen in the case of insects, but still more plainly with many crustaceans. When, however, we read of the several wonderful cases, recently discovered, of the so-called alternate generations of animals, we come to the climax of developmental transformation. What fact can be more astonishing than that a delicate branching coralline, studded with polypi and attached to a submarine rock, should produce, first by budding and then by transverse division, a host of huge floating jelly-fishes; and that these should produce eggs, from which are hatched swimming animalcules, which attach themselves to rocks and become developed into branching corallines; and so on in an endless cycle? Hence it will be seen that I follow those naturalists who look at all cases of alternate generation, as essentially modifications of the process of budding, which may supervene at any stage of development. This view of the close connection between alternate generations and ordinary metamorphoses has recently been much strengthened by Wagner's discovery of the larva of a Cecidomyia,— that is of the maggot of a fly,— producing asexually within its body other and similar larvæ; these again repeating the process. ↑ ↑

It has already been remarked that various parts and organs of the same individual animal are during an early embryonic period exactly like each other, but become in the adult state widely different and serve for widely different purposes. So again it has already been remarked that the embryos of distinct species and genera within the same class are generally closely similar, but become when fully developed widely dissimilar. A better proof of this latter fact cannot be given than that by Von Baer,

effected .. abruptly by a few stages; ... but the transformations are in reality numerous and gradual, though concealed. A certain ephemerous insect (Chlöeon) during its development, moults, as shown by Sir J. Lubbock, above twenty times, and each time undergoes a certain amount of change; and in this case we see the act of metamorphosis performed in a primary and gradual manner. ↑ Many insects, and especially certain crustaceans, show us what wonderful changes of structure can be effected during .. development. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. Such changes, however, reach their climax in the so-called alternate generations of some of the lower animals. It is, for instance, an astonishing fact that a delicate branching coralline, studded with polypi and attached to a submarine rock, should produce, first by budding and then by transverse division, a host of huge floating jelly-fishes; and that these should produce eggs, from which are hatched swimming animalcules, which attach themselves to rocks and become developed into branching corallines; and so on in an endless cycle. ↑ The belief in the essential identity of the process of alternate generation and of ordinary metamorphosis has .. been greatly strengthened by Wagners discovery of the larva or maggot of a fly, namely the Cecidomyia, producing asexually ... other and similar larvæ. .. .. .. .. .. ↑

It has already been stated that various parts and organs in the same individual are exactly like each other during an early embryonic period, but in the adult state become widely different and serve for widely different purposes. So again it has .. been stated that the embryos of the most distinct species within the same class are generally closely similar, but become when fully developed widely dissimilar. A better proof of this latter fact cannot be given than that by Von Baer,