namely, first, the difficulties of transitions, or how a simple being or a simple organ can be changed and perfected into a highly developed being or into an elaborately constructed organ;
lehenengo, iragaitzen zailtasunak, edo izaki xume bat edo organo xume bat nola alda eta hobe daitekeen, izaki oso garatu edo xehetasunez eraturiko organo bilakatzeraino;