The two books included under this title present more than the usual difficulties. They were not written by Aristotle in their original form; moreover the text of Bekker is very far removed from the original Greek. This was first translated into Arabic, and then into Latin. The present Greek text is a somewhat poor translation of the mediaeval Latin copy, which was itself an inferior translation of the Arabic. Still it has seemed best to translate the Greek text, as we have it, while admitting that it is often unsatisfactory, and sometimes unintelligible. In spite of these difficulties the books contain some things of great importance, especially the discussion on sex in plants.