170 ARISTOTLE S ANHOMCEOMEEIA 



one or more parts of these organs. That the hystera is 

 internal is clear from many passages, and especially from 

 G. A. i. c. 12, 719&, where it is stated that the hystera is 

 internal in all females, because of the need for guarding the 

 young animal and keeping it warm. Its meaning is clear 

 to this limited extent, but it is often difficult to decide to 

 what part or parts the term refers. In some cases it means 

 the uterus of a mammal, e.g., in H. A. vii. c. 4, s. 1, but in 

 many other passages it means the ovaries, or these and the 

 oviducts, of birds, reptiles, amphibians, fishes, cephalopods, 

 and crustaceans. 



Even when describing the organs of mammals he does 

 not always distinguish between the uterus and the ovaries, 

 and, in G. A. i. c. 3, 716&, he says that all hysterce are in 

 two parts, just as there are two testes in males. He also 

 mentions the hysterce in close connection and by way of 

 comparison with the testes. His fullest description of the 

 uterus of a mammal is in H. A. iii. c. 1, ss. 10 and 11. 

 It seems to be clear that he gave the name hystera 

 more particularly to the more external and the name 

 delphys to the innermost parts of the uterus, and that he 

 was acquainted with the cornua or horns of the uterus in 

 some animals, and with the twisted or waved parts of the 

 Fallopian tubes or oviducts. 



One of the most interesting passages relating to the 

 hystera of viviparous animals is that in which he records 

 the existence of placental animals. He says that the 

 hysterce of ruminants and also the hare, mouse, and bat, 

 among animals with front teeth in both jaws, have cotyle- 

 dones (placentas) in the pregnant hystera, and that all other 

 viviparous animals with feet and with front teeth in both 

 jaws have a smooth hystera, the foetus being attached to the 

 hystera itself and not to a cotyledon.* 



The animals in which the placentae are restricted to 

 circumscribed patches are much more numerous than 

 Aristotle believed, and among them may be specially 

 mentioned, in addition to those mentioned by Aristotle, the 

 Garni vora and Insectivora. 



In his short descriptions of the hysterce of birds, reptiles, 

 batrachians, and cartilaginous fishes, in H. A. iii. c. 1, ss. 12 

 and 13, he clearly refers to the oviducts communicating with 

 a single passage leading to the exterior. 



* H. A. iii. c. 1, s. 15. 



