ONTOGENESIS 213 



expressed by Haller in the "Elements of Physiology;" 

 "No part in the animal was formed before another: all 

 were created at the same time." " Against such contra- 

 dictory evidence as the metamorphoses of insects, the 

 preformationists had none but verbal weapons and 

 dogmatic opinions that found expression in the state- 

 ment that though it might not be in a visible form, still 

 the caterpillar contained in itself the pupa, and the pupa 

 the butterfly, therefore the butterfly was already present, 

 as such, in the caterpillar." 



Successive generations were accounted for by sup- 

 posing that the human ovary not only contained num- 

 bers of ova, each containing an individual in miniature, 

 but that in the ovary of this minature there were many 

 other and smaller miniatures, and within these still 

 others, and so on, like the Japanese nests of boxes, one 

 within another. "In the extension of this box-within- 

 box doctrine (Einschachtelungslehre) the distinguished 

 physiologist, Haller, calculated that God had created 

 together, 6000 years ago on the sixth day of his crea- 

 torial labors the .germs of 200,000,000,000 men,' and 

 ingeniously packed them all in the ovary of our venerable 

 mother Eve." This was, of course, all theory, but there 

 seemed to be no disposition to get at the true facts. The 

 theory of epigenesis, or development of the embryo, 

 taught by Hippocrates and Aristotle, was almost for- 

 gotten, until Caspar Frederich Wolff (1735-1794) again 

 brought it into prominence by studies of the developing 

 hen's egg, in which he found no preformed individual, 

 but one growing, transforming, and differentiating in a 

 manner easy of study and demonstration. In his doc- 

 tor's dissertation (1759) Wolff laid down the scientific 

 principle that what one could not recognize by means 

 of the senses was certainly not present preformed in the 

 germ. "At the beginning," so he maintained, "the 

 germ is nothing else than an unorganized material elimi- 

 nated from the sexual organs of the parent, which grad- 

 ually becomes organized, but only during the process 

 of development, in consequence of fertilization." 



