for instance, the canary-bird has been crossed with nine distinct species of finches, but, as not one of these breeds freely in confinement, we have no right to expect that the first crosses between them and the canary, or that their hybrids, should be perfectly fertile.
adibidez, kanaria bederatzi txonta espezie diferenterekin gurutzatu da, baina, hesipean hauetako bat bera ere eragozpenik gabe umatzen ez denez gero, ez dugu arrazoirik espero izateko haien eta kanariaren arteko lehen gurutzaketak, ezta haien hibridoak ere, erabat ugalkorrak izanen direnik.