as we are of those general phenomena which all living 

 cells exhibit, we could most profitably turn to the study 

 of those phenomena common to most or all living cells. The 

 experiments presented in this paper represent such a study. 



In various branches of biological science, progress 

 has been made by first studying structures md then attempt- 

 ing to discover the significance of these structures, and 

 while there is no intrinsic reason why it should, it seems 

 plausible that cell physiology may advance along the same 



b 



lines. At any rate, it can not be denied that the prolem 

 of the function of the -eeti nucleus, the most character- 

 istic structure of the cell, is one of the most alluring 

 problems of cell physiology, and as such it has excited 

 much speculation, and been the subject of some experiment- 

 al work. 



Before reviewing the experiments of previous workers 

 in this field, it might be well to call attention to a few 

 matters of common knowlege and observation which bear 

 upon the problem. The most obvious fact with regard to the 

 nucleus is that it almost invariably occupies a central 

 position in the cell, and no biologically trained man, 

 accustomed as he is to regard the smallest acts of nature 

 as significant, would fail to appreciate the importance of 

 this fact. Reflection upon the central position of the 

 nucleus leads to the conclusion that the nucleus must 



(6) 



