Book I of Aristotle's De partibus animalium, independent of the other three books, is a general introduction to Aristotle's biological work. However, the great importance of this text and the attention paid to its content by scholars is in sharp contrast to its neglect in terms of textual editing: previous editions have dealt with only a fraction of the tradition. This book therefore begins with the recensio of the manuscript tradition that has come down to us, reconstructing the genealogy of some 50 Greek manuscripts, an Arabic translation from the 9th century, as well as two medieval and two renaissance Latin translations. In addition, the independent textual witnesses - 25 Greek codices, the Arabic and the two medieval Latin translations - allow the text of two lost late antique copies, the Hyparchetypes a and ß, to be reconstructed. Their readings, the variants, are decisive for the constitution of the text. The first historical-critical new edition resulting from the examinatio of the text transmitted can improve the Louis edition of 1956 in more than 60 places.