It would be easy to show that there now exist carnivorous animals presenting close intermediate grades from strictly terrestrial to aquatic habits; and as each exists by a struggle for life, it is clear that each must be well adapted to its place in nature.
Erraz legoke frogatzen egun ere badaudela animalia haragijaleak, hertsiki lehortarrak diren azturetatik urtarretarainoko aztura maila guztiak erakusten dituztenak; eta nor bere biziaren alde borrokatuz existitzen bada, argi dago naturan duen lekura ongi moldaturik egon behar duela.