Page - 461 - in The Origin of Species

CLASSIFICATION 461 Monachanthus, Myanthus, and Catasetum, which had previ- ously been ranked as three distinct genera, were known to be sometimes produced on the same plant, they were immedi- ately considered as varieties ; and now I have been able to show that they are the male, female, and hermaphrodite forms of the same species. The naturalist includes as one species the various larval stages of the same individual, how- ever much they may differ from each other and from the adult, as well as the so-called alternate generations of Steen- strup, which can only in a technical sense be considered as the same individual. He includes monsters and varieties, not from their partial resemblance to the parent-form, but be- cause they are descended from it. As descent has universally been used in classing together the individuals of the same species, though the males and females and larvae are sometimes extremely different ; and as it has been used in classing varieties which have undergone a certain, and sometimes a considerable amount of modifica- tion, may not this same element of descent have been uncon- sciously used in grouping species under genera, and genera under higher groups, all under the so-called natural system? I believe it has been unconsciously used; and thus only can I understand the several rules and guides which have been followed by our best systematists. As we have no written pedigrees, we are forced to trace community of descent by resemblances of any kind. Therefore v^^e choose those char- acters which are the least likely to have been modified, in relation to the conditions of life to which each species has been recently exposed. Rudimentary structures on this view are as good as, or even sometimes better than, other parts of the organisation. We care not how trifling a character may be—let it be the mere inflection of the angle of the jaw, the manner in which an insect's wing is folded, whether the skin be covered by hair or feathers—if it prevail through- out many and different species, especially those having very different habits of life, it assumes high value; for we can account for its presence in so many forms with such differ- ent habits, only by inheritance from a common parent. We may err in this respect in regard to single points of structure, but when several characters, let them l)c ever so trifling,