Generation from the egg occurs in an identical manner in all birds, though the time taken to termination varies [At three days and a half] the head is apparent, and its eyes, very swollen; and this continues for a long time, for it is later that they contract and become smaller.

Aristotle, Historia Animalium VI (561a4–21)

中文翻译：

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开发和再生过程中的大小和规模。

所有鸟类以相同的方式从卵中产生，尽管终止所需的时间不同[三天半]头部明显，眼睛非常肿胀；这种情况会持续很长时间，因为它们会收缩变小。

亚里士多德，《动物史》VI (561a4–21)