But it would be superfluous to discuss this question in detail: for with plants we have conclusive evidence that the sterility of crossed species must be due to some principle, quite independent of natural selection.
izan ere, landareei dagokienez, erabateko frogak ditugu, gurutzaturiko espezieen antzutasuna, hautespen naturalarekin inolako zerikusirik ez duen hastapenen baten ondorio izan behar duela erakusten dutenak.