Origin of Species Variorum

Comparison with 1866

the relative proportional numbers of the high and low classes in the population of the world at the two periods: if, for instance, at the present day there be fifty thousand kinds of vertebrate animals, and if we knew that at some former period only ten thousand kinds had existed, we ought to look at this increase in number of the highest class, which implies a great displacement of lower forms, as a decided advance in the organisation of the world, whether the higher or the lower vertebrata had thus largely increased. We can thus see how hopelessly difficult it will apparently for ever be to compare with perfect fairness, under such extremely complex relations, the standard of organisation of the imperfectly-known faunas of successive periods of the earth's history.

We shall appreciate under one important point of view this difficulty the more clearly, by looking to the case of certain existing faunas and floras. From the extraordinary manner in which European productions have recently spread over New Zealand, and have seized on places which must have been previously occupied, we may believe, if all the animals and plants of Great Britain were set free in New Zealand, that in the course of time a multitude of British forms would become thoroughly naturalized there, and would exterminate many of the natives. On the other hand, from the progress of this displacement in New Zealand, and from hardly a single inhabitant of the southern hemisphere having become wild in any part of Europe, we may well doubt, if all the productions of New Zealand were set free in Great Britain, whether any considerable number would be enabled to seize on places now occupied by our native plants and animals. Under this point of view, the productions of Great Britain may be said to be higher than those of New Zealand. Yet the most skilful naturalist from an examination of the species of the two countries could not have foreseen this result.

Agassiz insists that ancient animals resemble to a certain extent the embryos of recent animals of

the relative proportional numbers of the high and low classes throughout the world at any two periods: if, for instance, at the present day .. fifty thousand kinds of vertebrate animals exist, and if we knew that at some former period only ten thousand kinds .. existed, we ought to look at this increase in number in the highest class, which implies a great displacement of lower forms, as a decided advance in the organisation of the world. .. .. .. .. .. .. .. .. .. .. .. We .. thus see how hopelessly difficult it is to compare with perfect fairness, under such extremely complex relations, the standard of organisation of the imperfectly-known faunas of successive periods. .. .. .. ..

We shall appreciate ... this difficulty the more clearly, by looking to ... certain existing faunas and floras. From the extraordinary manner in which European productions have recently spread over New Zealand, and have seized on places which must have been previously occupied, we must believe, that if all the animals and plants of Great Britain were set free in New Zealand, in the course of time a multitude of British forms would become thoroughly naturalised there, and would exterminate many of the natives. On the other hand, from ... hardly a single inhabitant of the southern hemisphere having become wild in any part of Europe, we may well doubt whether, if all the productions of New Zealand were set free in Great Britain, .. any considerable number would be enabled to seize on places now occupied by our native plants and animals. Under this point of view, the productions of Great Britain stand much higher in the scale than those of New Zealand. Yet the most skilful naturalist, from an examination of the species of the two countries could not have foreseen this result.

Agassiz and several other highly competent judges insist that ancient animals resemble to a certain extent the embryos of recent animals belonging to