That many breeds produced by man have to a large extent the character of natural species, is shown by the inextricable doubts whether many of them are varieties or aboriginally distinct species.

人类培育出的许多品种在很大程度上具有自然物种的特征，这一点可以从无法摆脱的疑问中看出， 其中许多品种是变种还是原始独特的物种。