We are so much accustomed to see a difference in structure between the embryo and the adult, that we are tempted to look at this difference as in some necessary manner contingent on growth.
Enbrioi eta helduaren arteko egitura-ezberdintasuna ikusten hain ohiturik gaudenez, aiher gara ezberdintasun hori hazkundearen mende nolabait derrigorrez dagoen gauzatzat hartzera.