220 The Unity of the Organism 



that growth determines division and not division growth." ^^ 

 And the author continues : "Each stage of the development 

 appears to stand in relation not only to what has preceded 

 it, but to what will succeed it, and is a link in a chain one 

 end of which is lost in the obscurity of the past while the 

 other stretches into the future." And still further: "We 

 must, I believe, recognize the fact so forcibly discussed by 

 Dr. Whitman in his lecture on the Inadequacy of the Cell- 

 Theory of Development and so clearly shown by centro- 

 lecitlial ova, that in embryological development the differ- 

 entiation which occurs is a differentiation of the entire or- 

 ganism and not of the constituent parts or cells of which 

 it is composed ; physiologicall}^, if not morphologically, 

 every organism is a syncytium, and future theories of 

 heredity must take this into consideration." 



I will do no more in the way of comment than to call 

 attention to the fact that the phrase "in embryological 

 development the differentiation which occurs is a differentia- 

 tion of the entire organism and not of the constituent parts 

 or cells," is one Avay of expressing specifically my general 

 proposition that the organism is an explanation of its parts 

 or cells. 



While the element alist may admit himself compelled to 

 grant that in animals having eggs of the type dealt with 

 by Hallez, Wheeler and McMurrich, i.e., eggs of the insect 

 type, the organism seems as mucli a causal explanation of 

 the cells as the cells are a causal explanation of the organ- 

 ism, he will be likely to say tliat eggs of this type are rather 

 the exception than the rule, taking the whole animal king- 

 dom into account, and hence that the cases cited do not 

 justify a sweeping generalization of the sort I am trying 

 to establish as to the causal power of tlie wliole over the 

 parts in organic development. 



We nmst consequently consider liow tills matter stands 

 with animals generally. Attention may first be called to 



