How, then, can we explain these several facts in embryology-namely, the very general, though not universal, difference in structure between the embryo and the adult;
Nola azaldu, bada, enbriologiako egitate ezberdinok? Hots, enbrioiaren eta helduaren arteko egitura-ezberdintasun oso orokorra, baina ez unibertsala, gertatzea;