for had this been the case they would have closely resembled each other in all respects. Thus the difficulty of an organ, apparently the same, arising in several remotely allied species, disappears, leaving only the lesser yet still great difficulty: namely, by what graduated steps these organs have been developed in each separate group of fishes.
Era horretan, organo bat, itxuraz berdina dena, kidetasun urruneko espezie ezberdinetan sortzearen zailtasuna ezabatu egiten da, beste zailtasun txikiago bat, nahiz eta hala ere handia, geratzen delarik, alegia, zeintzuk izan diren arrain talde bakoitzean organo hauek garatzeko egin behar izan diren mailakako urratsak.