One of Harvey's prime objects is to defend and establish, on the basis of direct observation, the opinion already held by Aristotle, that, in the higher animals at any rate, the formation of the new organism by the process of generation takes place, not suddenly, by simultaneous accretion of rudiments of all or the most important of the organs of the adult, nor by sudden metamorphosis of a formative substance into a miniature of the whole, which subsequently grows, but by epigenesis, or successive differentiation of a relatively homogeneous rudiment into the parts and structures which are characteristic of the adult.
In a well-known note to Charles Leopold Laurillard's Eloge, prefixed to the last edition of the Ossemens fossiles, the " radical de l'etre " is much the same thing as Aristotle's " particula genitalis " and Harvey's " ovum."
But in 1681 Gerard Blasius had brought out at Amsterdam an Anatome Animalium, containing the results of all the dissections of animals that he could find; and the second part of this book, treating of Volatilia, makes a respectable show of more than one hundred and twenty closely-printed quarto pages, though nearly two-thirds is devoted to a treatise De Ovo et Pullo, containing among other things a reprint of Harvey's researches, and the scientific rank of the whole book may be inferred from bats being still classed with birds.
The influence of Harvey's discovery began to be felt before the middle of the century.
His claim to have anticipated Harvey's discovery rests on no better authority than a memorandum, probably copied from Caesalpinus or Harvey himself, with whom, as well as with Bacon and Gilbert, he maintained a correspondence.
In physiological matters he is in advance of Aristotle and Galen, though we can hardly assert - as has sometimes been thought - that he anticipated Harvey's discovery of the circulation of the blood.