Thus it is rendered possible for the two sexes to be modified through natural selection in relation to different habits of life, as is sometimes the case; or for one sex to be modified in relation to the other sex, as commonly occurs.
Horrela gertagarri bihurtzen da hautespen naturalaren bidez sexu biak bizi-aztura diferenteekiko eraldatuak izatea, batzuetan jazotzen den moduan; edo baita sexu bat bestearekiko eraldatua izatea ere, arruntki jazotzen den moduan.