Correlative Differentiation and Growth 47 



nection between the nuclei of the two partial networks 

 belonging to these parts, a fact which renders these net- 

 works in certain respects quite independent of one another 

 if at the same time they do not come from a common 

 principal branch. 



It would be "a very important matter," writes Delage 

 "to know if secondary protoplasmic connections are 

 formed between neighboring cells which are not sisters 

 but which have been brought only secondarily into contact 

 with one another, for example after an mvagination in 

 animals or through grafting in plants." 24 In the cases 

 in which this did not occur one could then have the 

 simultaneous and to a certain extent independent exist- 

 ence of partial circulatory systems even though they lie 

 close together or perhaps even enclose each other. 



Roux designates by the term "correlative or dependent 

 differentiation" the complete or partial determination of 

 development by reciprocal influences of epigenetic nature 

 which become established, in a certain measure at least 

 as he admits himself, between, the cells. We can then 

 designate these partial networks of the general cir- 

 culatory system by the name "networks of correlation." 

 And we shall see that, conformably with our theoretical 

 conjectures very many processes seem actually to prove 

 that each of these networks is capable of existence by 

 itself, independent within certain limits of other partial 

 networks. 



Among the phenomena of correlative differentiation 

 in development belong also those which are called com- 

 pensatory growths. The investigations of Ribbert ( 1889) 

 and his pupils upon the mammals have shown especially 



"Delage: L'heredite et les grands problemes de la biologic gen- 

 erale. P. 33. 



