The general sterility of crossed species may safely be looked at, not as a special acquirement or endowment, but as incidental on changes of an unknown nature in their sexual elements.
Gurutzaturiko espezieen antzutasun orokorra ziurtasunez har daiteke, ez lorpen edo dohaintzat, sexu-elementuetan izaniko aldaketa ezezagunen ondorio intzidentaltzat baizik.