On Animals, Books 13-26

and the soul, and that not every male produces semen, even though every female has menstrual fluid or something in place of menstrual fluid . . . . . . § 76-80, p. 1102-1106
Ch. 16. And it is a digression clarifying the opinion of the later Peripatetics followers of Aristotle concerning the diversity of egg-laying creatures and concerning the power of the semen and the animation of embryos . . . . . § 81-88, p. 1106-1110
Ch. 17. And it is a digression clarifying why the male and female are required for the generation of an animal and that the rational soul can have no creative principle at all in the semen due to its separation . . . . . . . . . . . . . . . . . . § 89-91, p. 1110-1112
Treatise II, which is concerning the cause of the sterility of animals and concerning the generation of similar members i.e., uniform or simple body parts, such as blood or bone . . . . . . . . . . . § 92-151, p. 1112-1144
Ch. 1. Concerning the causes of sterility occurring on the part of the male organ, and on the part of the womb in the female, and concerning the manner of the creation of the embryo in the womb from which it is generated, and according to what order the members are distinguished within it . . . . . . . . . . . . . . . . . . . . . . . § 92-100, p. 1112-1117
Ch. 2. For what reason the female in animals cannot generate by herself without the male, and concerning the generation, distinction, and completion of the members . . . . . . . . . . . . . . . . . . § 101-107, p. 1118-1121
Ch. 3. Concerning the distinction of the cause for which a thing is what it is, and what is sought in eternal things and what is not, and according to which manner and for what reason the heart is said to be the principle of the members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . § 108-112, p. 1121-1124
Ch. 4. Concerning the manner of the generation of uniform members from the heat of the heart and the complexional coldness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . § 113-118, p. 1124-1127
Ch. 5. Concerning the construction of the head and of the members that are in the head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . § 119-121, p. 1127-1129
Ch. 6. In what way the dominant members are formed after the heart, and after these, other members are formed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . § 122-126, p. 1129-1131
Ch. 7. In what way the increase of the embryo occurs through the cotyledons placental attachments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . § 127-129, p. 1131-1133
Ch. 8. Which animals are impregnated by their own intercourse and which are not, and concerning the causes of sterility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . § 130-133, p. 1133-1135
Ch. 9. Concerning the cause of the sterility of mules according to Democritus and Empedocles, and concerning the refutation of their opinion . . . . . . . . . . . . . . . . . . . . . . . . . . . . § 134-139, p. 1135-1138
Ch. 10. Concerning the true cause of the sterility of mules gathered from the consideration of the horse and the donkey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . § 140-144, p. 1139-1141
Ch. 11. And it is a digression collecting the summary of what has been said above in this treatise and assigning the causes so that what has been said previously may be better understood . . . . § 145-151, p. 1141-1144
Book 17, which is concerning the cause of egg-laying creatures and eggs . . . . . . . . . . . § 1-84, p. 1145-1190
Treatise I is concerning egg-laying birds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . § 1-45, p. 1145-1169
Ch. 1. Concerning those that lay many eggs and those that lay few, and concerning their physical cause . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . § 1-7, p. 1145-1148