Origin of Species Variorum

insensible series; and a series impresses the mind with the idea of an actual passage.

Hence I look at individual differences, though of small interest to the systematist, as of the highest importance for us, as being the first steps towards such slight varieties as are barely thought worth recording in works on natural history. And I look at varieties which are in any degree more distinct and permanent, as steps towards more strongly-marked and .. permanent varieties; and at the latter, as leading to sub-species or species. The passages from one stage of difference to another may, in some cases, be the simple result of the long-continued action of different physical conditions; but in most cases they may be attributed to the gradual accumulative action of natural selection, as hereafter to be more fully explained, on fluctuating variability. ↑ Hence a well-marked variety may be called an incipient species; but whether this belief is justifiable must be judged of by the general weight of the .. facts and considerations given throughout this work.

It need not be supposed that all varieties or incipient species necessarily attain the rank of species. They may ... become extinct, or they may endure as varieties for very long periods, as has been shown to be the case by Mr. Wollaston with the varieties of certain fossil land-shells in Madeira, and with plants by Gaston de Saporta. If a variety were to flourish so as to exceed in numbers the parent species, it would then rank as the species, and the species as the variety; or it might come to supplant and exterminate the parent species; or both might co-exist, and both rank as independent species. But we shall hereafter return to .. this subject.

From these remarks it will be seen that I look at the term species as one arbitrarily given, for the sake of convenience, to a set of individuals closely resembling