NUCLEO-CYTOPLASMIC RELATION OF OXYTRICHA 5 



(Protozoa). It is the latter application of the nucleo-cytoplas- 

 mic relation theory which is considered in the present study. 



The studies on pedigreed races of various Protozoa, under con- 

 ditions in which occur, sooner or later, a gradual decline in the 

 power of reproduction and finally death, have shown diverse re- 

 sults in regard to the absolute variations in size of the cells and 

 their nuclei and also in regard to the relative changes in size 

 of cytoplasm and nucleus during the various phases of reproduc- 

 tive activity. 



For example, Maupas ('88) in his extensive studies on the life 

 histories of various Infusoria found a decrease in size of the cells 

 and an increase in the size of the nuclei as the organisms proceeded 

 to what he termed 'senile degeneration.' Calkins ('02, '04) from 

 studies on the life history of Paranifiecium caudatum, in which he 

 followed with great care several races of this species through a 

 number of depression periods which finally culminated in death, 

 stated that "The first clearly marked period of depression 

 . wUs characterized by a well-defined reduction in 

 size (down to 109 microns), and by vacuolization of the endo- 

 plasm .... " ('04, p. 443). Concerning the animals in 

 later periods of low fission rate he wrote: "These became smaller 

 and smaller," and again: "These unstimulated individuals died 

 out in about 508 generations after becoming much emaciated and 

 reduced in size and with reduced nuclei" (p. 444). 



Popoff ('07) in his study of the life history of Stylonychia 

 mytilus and of Paramaecium caudatum clearly described and 

 illustrated a marked decrease in size of the cells as degeneration 

 proceeded and this was accompanied by a marked increase in 

 size of the nuclei. Similarly, in his work on Frontonia leucas 

 r08) he found that slow division rate was accompanied by a 

 decrease in cell size and increase in nuclear size. On the other 

 hand. Woodruff ('05) found a marked increase in cell size as 

 well as an increase in nuclear size during the life of a pedigreed 

 race of Oxytricha fallax,i and Gregory ('09) in her study of the 



1 In the very last stage of degeneration, when the two or three remaining cells 

 of the race were unable to divide at all, there was a marked shrinking before 

 death occurred. This, obviously, has no bearing on the present problem. 



