80 ROBERT W. HEGNER 



from his investigations of Oxytricha fallax. In this cihate 

 "The size of the cell and the size of the nucleus as well as the 

 nucleocytoplasmic relation are interpreted as an incidental 

 result rather than a cause of the rate of cell division" (p. 22). 



Only a few scattered studies of the chromatin-cytoplasm 

 relation have been published, and these are for the most part 

 unsatisfactory. Boveri ('02), as mentioned above, attributed 

 cell size in larval sea-urchins to chromatin number; whereas, 

 Erdmann ('09), who also studied sea-urchins' eggs, concludes 

 that the chromatin mass rather than the number of chromo- 

 somes is the size-determining factor. In plants also the rela- 

 tion between chromatin mass, chromosomes, and cell size have 

 been considered. Gates ('09), for example, believes that the 

 cells of Oenothera gigas are large because of the double number 

 of chromosomes present, and not merely because of an increase 

 in chromatin mass. 



The theory offered by Hertwig to account for the various 

 complex processes that occur during. the life cycles of the Pro- 

 tozoa appears at first plausible, but will not withstand close 

 analysis. The data are entirely inadequate to sustain the 

 claims of the theory, but investigations of the actual relations 

 of nucleus, chromatin, and cytoplasm to one another and their 

 relations to external heritable characteristics are very desirable, 

 especially since thay may throw light upon the important genetic 

 studies of the Protozoa that have been published, especially 

 by Jennings and his students. 



^. Nucleocytoplasmic relations in Arcella 



All of the data gathered together in the course of the investi- 

 gations herein described favor the hypothesis that within a 

 certain line of a certain species of Arcella there is a definite 

 quantitative relation between nucleus and cytoplasm. Of 

 interest in this connection is the fact. that in both binucleate 

 and multinucleate specimens the nuclei, although free to move 

 about within the cytoplasmic mass, become arranged in such 

 a manner that they are equidistant from one another, and 



