It is certainly true, that new organs appearing as if created for some special purpose rarely or never appear in any being; as indeed is shown by that old, but somewhat exaggerated, canon in natural history of "Natura non facit saltum."
Izan ere, egia da, xede berezi baterako sortua edo ematen duen organo berririk oso bakanki edo sekula ere ez dela agertzen ezein izaki bizidunetan, "Natura non facit saltum" natur historiako harako arau zahar eta larregizko samar hark ere adierazten duen moduan.