EXPERIMENTAL MORPHOGENESIS 



69 



But if regulation has restored, on a smaller scale, the whole 

 of the arrangement according to all values of x, y and z, 

 development also can take place completely (Fig. 7). 



Fio. 7. DIAGRAM ILLUSTRATING THE INTIMATE REGULATION or PROTOPLASM FROM 



"HALF "TO "WHOLE." 



The large circle represents the original structure of the egg. In all cases where cleavage- 

 cells of the two-cell stage are isolated this original structure is only present as 

 "half" in the beginning, say only on the right (+y) side. Development then 

 beco7nes "half," if the intimate structure remains half; but it becomes "whole" 

 (on a smaller scale) if a new whole-structure (small circle !) is formed by regulatory 

 processes. 



I am quite aware that such a discussion is rather empty 

 and purely formal, nevertheless it is by no means without 

 value, for it shows most clearly the differences between what 

 we have called the intimate structure of germs, responsible 



