SECT. I] EMBRYOLOGY IN ANTIQUITY 59 



hatching chick, and if he had given this fact a little more prominence 

 he could hardly have come to enunciate the general theory of 

 birth which appears in the above passage. Moreover, had he been 

 acquainted with the circulation of the maternal and foetal blood in 

 viviparous animals, he could hardly have held that there was less 

 food in a given amount of maternal blood at the end of development 

 than at the beginning. At any rate, his attempted theory of birth 

 was a worthy piece of scientific effort, and we cannot at the present 

 moment be said to understand fully the principles governing incuba- 

 tion time (see p. 470). 



The treatises on food and on flesh, trepl Tpo(f>rj<i and irepl aapKcovy 

 are both late additions to the Hippocratic corpus, but contain points 

 of embryological interest. Section 30 of the former contains some 

 remarks on embryonic respiration, and Section 3 of the latter has a 

 theory of formation of nerves, bones, etc. by difference of composition 

 of glutinous substances, fats, water, etc. Section 6 supports the view 

 that the embryo is nourished in utero by sucking blood from the 

 placenta, and the proof given is that its intestine contains the 

 meconium at birth. Moreover, it is argued, if this were not so, how 

 could the embryo know how to suck after it is born? 



1-4. Aristotle 



After the Hippocratic writings nothing is of importance for our 

 subject till Aristotle. It is true that in the Timaeus Plato deals with 

 natural phenomena, eclectically adopting opinions from many pre- 

 vious writers and welding them into a not very harmonious or logical 

 whole. But he has hardly any observations about the development 

 of the embryo. The four elements, earth, fire, air, and water, are, 

 according to him, all bodies and therefore have plane surfaces which 

 are composed of triangles. Applying this semi-atomistic hypothesis 

 to the growth of the young animal, he says, "The frame of the entire 

 creature when young has the triangles of each kind new and may 

 be compared to the keel of a vessel that is just ofT the stocks ;^ they 

 are locked firmly together and yet the whole mass is soft and delicate, 

 being freshly formed of marrow and nurtured on milk. Now when 

 the triangles out of which meats and drinks are composed come in 

 from without, and are comprehended in the body, being older and 

 weaker than the triangles already there, the frame of the body gets 

 the better of them and its newer triangles cut them up and so the 



