150 EMBRYOLOGY IN THE SEVENTEENTH [pt. ii 



demonstrate by powerfull arguments that the Foetus doth not receive 

 its Vital Spirits by the arteries from the Mother, and hath fully 

 answered those arguments which are alledged to the contrary. But 

 he might also as well have proved by the same arguments that the 

 blood neither is transported into the Foetus from the mother's veines 

 by the propagations of the umbilicall veins which is made chiefly 

 manifest by the examples drawn from the Hen-Egge and the Caesarean 

 Birth." 



The least satisfactory parts of Harvey's book are the Exercitations 

 Lxxi and lxxii on the innate heat and the primigenial moisture. 

 Here he becomes very wordy and highly speculative, and gives us 

 little but a mass of groundless arguments. He devotes many pages 

 to proving that the innate heat is the blood and to drawing distinc- 

 tions between blood and gore, the one in the body, the other shed. 

 In one place he speaks of the processes of generation as so divine 

 and admirable as to be "beyond the comprehension and grasp of 

 our thoughts or understanding". Two centuries previously Frasca- 

 torius had said precisely the same thing about the motion of the heart, 

 and it was ironical that the very man who let the light in on cardiac 

 physiology should in his turn despair of the future of our knowledge 

 of embryonic development. 



Harvey did not say much about foetal respiration, and his few 

 remarks are contained in one of the "additional discourses". He is 

 puzzled exceedingly by the question. But he comes very near indeed 

 to the truth when he says, "Whosoever doth carefully consider these 

 things and look narrowly into the nature of aire, will (I suppose) 

 easily grant, that the Aire is allowed to animals, neither for refrigera- 

 tion, nor nutrition sake. For it is a tryed thing, that the Foetus is 

 sooner suffocated after he hath enjoyed the Aire, than when he was 

 quite excluded from it, as if the heat within him, were rather inflamed 

 than quenched by the aire". Had Harvey pursued this line of thought, 

 and looked still more narrowly into the nature of air, he might have 

 anticipated Mayow. He does say that he proposes to treat of the 

 subject again, but he never did. 



The mainspring of Harvey's researches on the does and hinds can 

 be realised by a reference to Rueff's figures in Fig. 6. According 

 to the Aristotelian theory, the uterus after fertile copulation would 

 be full of blood and semen ; according to the Epicurean theory (held 

 by the "physitians") it would be full of the mixed semina. If this 



