It is also necessary to bear in mind that, owing to the law of correlation, when one part varies and the variations are accumulated through natural selection, other modifications, often of the most unexpected nature, will ensue.
Kontuan hartu behar dugu, halaber, korrelazio legearen eraginez, atal bat aldatzen denean eta hautespen naturalez aldaketak metatzen direnean, beste eraldaketa batzuk ere agertuko direla, maiz ustegabeko izaeradunak.