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.

这个主题与人物的层次密切相关， 通常伴随着功能的变化，例如，鱼鳔转变为肺， 这些要点在上一章的两个标题下进行了讨论。