86 EMBRYOLOGY IN ANTIQUITY [pt. ii 



shaping of the embryo in the womb". But Galen was now to weld 

 together all the biological knowledge of antiquity into his voluminous 

 works, and so transmit it to the Middle Ages. 



Most of Galen's writing was done between a.d. 150 and 180. Out 

 of the twenty volumes of Kiihn's edition of 1829, l^^s than one is 

 concerned with embryology, a proportion considerably less than in 

 the case of Aristotle. Galen's embryology is to be found in his 

 Trepl (f)V(nKcov Svvdfiecov, On the Natural Faculties, which contains the 

 theoretical part, and in his On the Formation of the Foetus, which con- 

 tains the more anatomical part. There is also the probably spurious 

 treatise et ^mov to Kara <yaa-Tp6<i, On the Question of whether the Embryo 

 is an Animal. 



It is important to realise at the outset that Galen was a vitalist 

 and a teleologist of the extremest kind. He regarded the living being 

 as owing all its characteristics to an indwelling Physis or natural 

 entity with whose "faculties" or powers it was the province of 

 physiology to deal. The living organism according to him has a kind 

 of artistic creative power, a t6xvv> which acts on the things around 

 it by means of the faculties, Swd/xei's, by the aid of which each part 

 attracts to itself what is useful and good for it, rb oUelov, and 

 repels what is not, to aXXorptov. These faculties, such as the "peptic 

 faculty" in the stomach and the "sphygmic faculty" in the heart, 

 are regarded by Galen as the causes of the specific functions or 

 activity of the part in question. They are ultimate biological cate- 

 gories, for, although he admits the theoretical possibility of analysing 

 them into simpler components, he never makes any attempt to do 

 so, and evidently regards such an effort as doomed to failure, unlike 

 Roux, whose "interim biological laws" are really conceived of as 

 interim. "The effects of Nature", says Galen, "while the animal is 

 still being formed in the womb are all the different parts of the body, 

 and after it has been born an effect in which all parts share is the 

 progress of each to its full size and thereafter the maintenance of 

 itself as long as possible." Galen divides the effects of the faculties 

 into three. Genesis, Growth, and Nutrition, and means by the first 

 what we mean by embryogeny. "Genesis", he says, "is not a simple 

 activity of Nature, but is compounded of alteration and of shaping. 

 That is to say, in order that bone, nerve, veins, and all other tissues 

 may come into existence, the underlying substance from which the 

 animal springs must be altered; and in order that the substance so 



