VI EVOLUTION IN BIOLOGY 189 



Harvey proceeds to contrast this view with that 

 of the " Medici," or followers of Hippocrates and 

 Galen, who, " badly philosophising," imagined that 

 the brain, the heart, and the liver were simul- 

 taneously first generated in the form of vesicles ; 

 and, at the same time, while expressing his 

 agreement with Aristotle in the principle of epi- 

 genesis, he maintains that it is the blood which is 

 the primal generative part, and not, as Aristotle 

 thought, the heart. 



In the latter part of the seventeenth century, 

 the doctrine of epigenesis, thus advocated by 

 Harvey, was controverted, on the ground of direct 

 observation, by Malpighi, who affirmed that the 

 body of the chick is to be seen in the egg, before 

 the punctum sanguineum makes it appearance. 

 But, from this perfectly correct observation a con- 

 clusion which is by no means warranted was drawn ; 

 namely, that the chick, as a whole, really exists in 

 the egg antecedently to incubation ; and that what 

 happens in the course of the latter process is no 

 addition of new parts, " alias post alias natas," as 

 Harvey puts it, but a simple expansion, or unfold- 

 ing, of the organs which already exist, though they 

 are too small and inconspicuous to be discovered. 

 The weight of Malpighi's observations therefore 

 fell into the scale of that doctrine which Harvey 

 terms metamorphosis, in contradistinction to epi- 

 genesis. 



The views of Malphigi were warmly welcomed, 



