SECT. 3] AND EIGHTEENTH CENTURIES 143 



him that this is the case. For instance, he enquires why heat will 

 develop a chick out of a good egg but will only make a bad one worse. 

 "Give me leave to add something here", he writes, "which I have 

 tried often; that I might the better discerne the scituation of the 

 foetus and the liquors at the seventeenth day to the very exclusion. 

 I have boiled an eggc till it grew hard, and then pilling away the 

 shell and freeing the scituation of the chicken, I found both the 

 remaining parts of the white, and the two parts of the yolk of the 

 same consistence, colour, tast, and other accidents, as any other stale 

 egge, thus ordered, is. And upon this Experiment, I did much ponder 

 whence it should come to passe that Improlifical eggs should, from 

 the adventitious heat of a sitting Henne, putrifie and stink; and yet 

 no such inconvenience befall the Prolifical. But both these liquors 

 (though there be a Chicken in them too, and he with some pollution 

 and excrement) should be found wholesome and incorrupt; for that 

 if you eat them in the dark after they are boyled, you cannot dis- 

 tinguishe them from egges that are so prepared, which have never 

 undergone the hen's incubation." Harvey was never afraid of trying 

 such tests on himself; in another place, for example, he says, "Eggs 

 after 2 or 3 days incubation, are even then sweeter relished than stale 

 ones are, as if the cherishing warmth of the hen did refresh and 

 restore them to their primitive excellence and integrity". "And the 

 yolke (at 14 days) was as sweet and pleasant as that of a newlaid 

 cgge, when it is in like manner boyled to an induration." Another 

 matter on which Harvey set Fabricius right was on the question 

 whether at hatching the hen helps the chicken out or the chicken 

 comes out by itself. The latter was the belief held by Harvey, who 

 said of Fabricius' arguments on this point that they were "pleasant 

 and elegant, but not well bottomed". 



On the great question of preformation v. epigenesis, Harvey keenly 

 argued in favour of the latter view. "There is no part of the future 

 foetus actually in the egg, but yet all the parts of it are in it poten- 

 tially. ... I have declared that one thing is made out of another two 

 several wayes and that as well in artificial as natural productions, 

 but especially in the generation of animals. The first is, when one 

 thing is made out of another thing that is pre-existent, and thus a 

 Bedstead is made out of Timber, and a Statue out of a Rock, where 

 the whole matter of the future fabrick was existent and in being, 

 before it was reduced into its subsequent shape, or any tittle of the 



