352 " William E. Kellicott 



It is quite possible, therefore, that the normal growth of the indi- 

 vidual tissue or organ may be similarly regulated by the presence or 

 absence of specific internal secretions formed in various parts of the 

 body, \ATiether these secretions cause growth to continue by their 

 presence or by their absence could be told only through experiment, the 

 relation might differ with different parts, but the general hypothesis 

 of the control of normal growth through internal secretions seems legiti- 

 mate and may afford a simple explanation of the growth of the organism 

 as a composite collection of more or less independently growing units. 

 The data presented here seem to give morphological evidence of a control 

 of some such nature. 



Woods Hole, Mass., August, 1908. 



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