This subject is intimately connected with that of the gradation of the characters, often accompanied by a change of function, for instance, the conversion of a swim-bladder into lungs, points which were discussed in the last chapter under two headings.
Arazo hau hertsiki loturik dago maiz funtzio-aldaketa-adibidez, igeri-maskuria birika bilakatzea-lagun izan ohi duen ezaugarri mailaketarekin, aurreko kapituluan bi izenburupean eztabaidatu diren puntuak berauek.