200 EMBRYOLOGY IN THE SEVENTEENTH [pt. ii 



Haller remarks gently that he has searched for these phenomena in 

 vain. Vallisneri asserted the same kind of thing about the mammahan 

 ovum, though he admitted that, in spite of long searching, he had 

 never seen one. Besides the main distinction between prefer mationists 

 and epigenesists, then, there arose a division among the former 

 group, so that the ovists regarded all embryos as being produced 

 from smaller embryos in the unfertilised eggs, while 

 the animalculists regarded all embryos as being 

 produced from the smaller embryos provided by 

 the male in his spermatozoa. The animalculists 

 thus afforded a singular example of a return to 

 the ancient theory mentioned by Aeschylus in the 

 Oresteia (see p. 65). Their most conspicuous ex- 

 ample was Nicholas Andry, who pictured each 

 c^gg as being arranged like the Cavorite sphere in 

 which H. G. Wells' explorers made their way to the 

 moon, i.e. with one trap-door. The spermatozoa, 

 like so many minute men, all tried to occupy an 

 egg, but as there were far fewer eggs than sperma- 

 tozoa, there were, when all was over, only a few 

 happy animalcules who had been lucky enough 

 to find an empty egg, climb in, and lock the door 

 behind them. 



The whole controversy was intimately bound 

 up with the question of spontaneous generation, 

 for, whatever the case might be in the higher 

 animals, if it were true that the lower ones could arise de novo 

 out of slime, mud, or meat infusion, for instance, then their parts 

 at least must have been made by epigenesis, and not in any other 

 way, for it could hardly be held that a homogeneous infusion had 

 any structure of that kind. And if epigenesis could occur in the lower 

 animals, then the thin end of the wedge had been driven in, and it 

 might occur among the higher ones as well. It was in this way that 

 the spontaneous generation controversy came to have a peculiar 

 importance for embryology in the eighteenth century. Driesch has 

 essayed to make the generalisation that all the supporters of epigenesis 

 were vitalistic in their tendencies, while those who adhered to the 

 preformation theory were not. But there are too many exceptions 

 to this rule to make it of any use. In so far as there is truth in it. 



Fig. 1 1 . Hartsoeker's 

 drawing of a human 

 spermatozoon. 



