Centroepigenesis Accords with General Phenomena 69 



normal circumstances which have made them independent 

 of each other, two distinct nodal points, two central 

 zones of development. The necessary consequences of 

 the independent action of these two centers of develop- 

 ment would be the centration of each individual by itself. 

 On the other hand, the similarity of the two first blasto- 

 meric nuclei, which through multiplication give rise to 

 both of the two central zones concerned, would bring 

 about a similarity of the formative actions given off from 

 these zones. Therefore those formative stimuli which 

 act upon all points of any one of the infinite number of 

 planes symmetrical in relation to these centers, would 

 offset and annul one another, because they would be 

 equal and opposite but only in so far as they do act 

 along these planes. In this way could be explained why 

 the parts lacking in both individuals must always be alike. 



While thus all these different facts which have at- 

 tracted the careful attention of Roux and been made the 

 special object of his studies confirm, some directly others 

 indirectly, the hypothesis of centroepigenesis with ram- 

 ifying and independent networks of correlation, a further 

 support, indirect indeed, but nevertheless very real, will 

 be brought forward in the following chapter. For we 

 shall endeavor there to show that if a whole series of 

 facts compels us to throw over preformation, a series of 

 other facts forces us to throw over simple epigenesis also, 

 and this would give a high degree of probability to any 

 other hypothesis with which both series of facts should 

 be in accord. 



Finally, the symmetrical disposition which the greater 

 number of organisms present in relation to a point, to a 

 straight line, or to a plane, and also the advance of 

 growth along diverging ramifications, which indeed is a 



