For these species, from belonging to distinct families, would have differed to a certain extent, and in accordance with the principle that the nature of each variation depends on two factors, viz., the nature of the organism and that of the surrounding conditions, their variability assuredly would not have been exactly the same.
izan ere, espezieok, familia diferentekoak izaki, ezberdinak izanen ziren hein batean, eta, aldakuntzaren izaera faktore biren, hau da, organismoaren eta inguruko baldintzen izaeraren mende dagoela dioen hastapenaren arabera, haien aldagarritasuna, ziur, ez zen berbera izanen.