64 EMBRYOLOGY IN ANTIQUITY [pt. ii 



does not here anticipate the form of the recapitulation theory, but 

 he certainly suggests the essence of it in perfectly clear terms. This 

 chapter has also an interest for the history of theological embryology, 

 for its description of the entry of the various souls into the embryo 

 was afterwards made the basis for the legal rulings concerning 

 abortion. This chapter also discusses embryogeny as a whole, as does 

 the succeeding one. Chapter 5 is a digression into the problem 

 of why fertilisation is necessary by the male, but it has also some 

 curious speculations as to what extent the hen's egg is alive, if it is 

 infertile. The main thread is resumed in chapters 6 and 7, two very 

 fine ones, in which embryogeny and foetal nutrition are thoroughly 

 dealt with, but dropped again in the last section, chapter 8, which 

 is devoted to an explanation of sterility. This ends the second book. 



The third book is chiefly concerned with the application of the 

 general embryological principles described in the previous book to 

 the comparative field, and the fourth book contains a collection of 

 minor items which Aristotle has not been able to speak of before. 



But if the work as a whole tails off in a rather unsatisfactory 

 manner, its merits are such that this hardly matters. The extra- 

 ordinary thing is that, building on nothing but the scraps of specula- 

 tion that had been made by the Ionian philosophers, and the 

 exiguous data of the Hippocratic school, Aristotle should have pro- 

 duced, apparently without effort, a text-book of embryology of 

 essentially the same type as Graham Kerr's or Balfour's. It is even 

 very possible that Aristotle was unacquainted with any of the Coan 

 school, for, though he often mentions Democritus, Anaxagoras, 

 Empedocles and even Polybus, yet he never once quotes Hippo- 

 crates, and this is especially odd, for Aristotle is known to have 

 collected a large library. Probably Hippocrates was only known to 

 Aristotle as an eminent medical man; if this is so, Aristotle's achieve- 

 ments are still more wonderful. 



The depth of Aristotle's insight into the generation of animals has 

 not been surpassed by any subsequent embryologist, and, con- 

 sidering the width of his other interests, cannot have been equalled. 

 At the same time, his achievements must not be over-estimated. 

 Charles Darwin's praise of him in his letter to Ogle (which is too 

 well known to quote) is not without all reservations true. There is 

 something to be said for Lewes as well as Piatt. Aristotle's con- 

 clusions were sometimes not warranted by the facts at his disposal, 



