SECT, i] EMBRYOLOGY IN ANTIQUITY 73 



while the white was cold. He held also that the bird embryo always 

 developed at the pointed end; no doubt, as Piatt has suggested, 

 Aristotle belonged to Swift's class of "Little-endians", and must have 

 always opened them at that end, in which case he would find the 

 embryo there, for the yolk always swims embryo uppermost. He 

 knew also that the yolk liquefied during the first week of develop- 

 ment, and that it grew larger, but he did not guess the right reasons 

 of these phenomena. He knew the arrangements for embryonic 

 development in the dolphins and ovo viviparous sharks. He takes 

 a strong line over spontaneous generation; "nothing", he says, 

 "comes into being by putrefying, but by concocting". And so in 

 many other passages where detailed observation is joined with acute 

 reasoning. So far only the treatise on the generation of animals 

 has been under consideration. But in the irepl ^oiwv, also, there are 

 many embryological data, and it is strange that those detailed 

 observations upon the developing fowl embryo, which demonstrate 

 more than anything else Aristotle's wonderful powers of observation, 

 are not contained at all in the Generation of Animals, but in the History 

 of Animals. He takes animals one by one in order, and in each case 

 deals with their generative peculiarities, such as their mode of 

 hatching, their incubation period, their fertility, etc. For instance, 

 he correctly relates how cartilaginous fish embryos possess a yolk-sac 

 like bird embryos, but no allantois. In his account of the fowl he is 

 unusually precise. 



Most of the sixth book is occupied with the account of the genera- 

 tion of birds and fishes, and the seventh treats also very fully of that 

 of man. But in both cases it is a description that is given; more 

 theoretical considerations are left to the book on generation, and for 

 this reason the latter work is the more interesting. From a general 

 point of view the History of Animals has a more wonderful wealth 

 of material in it than the book on generation, but, at the same time, 

 it also indulges in much more extravagant stories, such as those of 

 the "kindly and gentle dolphin" and the equine Oedipus, and to 

 that extent the austerity of the book on generation charms us more. 



Other treatises also mention embryology. The irepl ^(owv fioployvj On 

 the Parts of Animals, has a passage in which the appearance of the 

 third-day chick embryo is described, and refers to observations on 

 the lack of pigment and of distinct medullary canals in bones in 

 foetal life. The small work entitled Trepl dvairvoTj^;, On Respiration, also 



