DIFFERENT SYSTEMS. 89 



•misfortunes, he loft, among other papers, what 

 he had written concerning the generation of in- 

 feds; and it appears, that he compol'ed from 

 memory his treatile on the generation of birds, 

 and of quadrupeds, i ihall give a lliort view of 

 his remarks, of his experiments, and of his the- 

 ory. 



Harvey alledges, that men, and all other ani?- 

 mals, proceed from eggs; that, in viviparous a- 

 nimals, the firft produce ot conception is a kind 

 of egg; and that the only difference between 

 the viviparous and oviparous is, that, in the for- 

 mer, the foetufes begin to exiil, increafe, and 

 acquire [heir full grov\ th in the uterus; but that, 

 in the oviparous animals, the rudiments of the 

 foetufes begin to exift in the body of the mother, 

 where they are in the form of eggs; and it is 

 only after their exclulion that they become real 

 foetufes. And it defer ves to be remarked, fays 

 he, that, in oviparous animals, fome retain their 

 eggs till they be perfedt, as birds, ferpents, and 

 oviparous quadrupeds; and that others exclude 

 their eggs before they are perfedf , as fiihes, cruf- 

 taccous and teftaceous animals. The eggs laid 

 by thefe creatures are only the rudiments of eggs, 

 which afterwards acquire membranes and a 

 white, and attraQ nouriihment from the matter 

 with which they are furroundcd. There are even, 

 he adds, infeds, caterpillars, for example, which 

 are only imperfed eggs; they fearch for their 

 nourilliincn't, and, at the end of a certain "time, 



they 



