NUCLEO-CYTOPLASMIC RELATION OF OXYTRICHA 7 



different phases of reproductive activity illustrated in my earlier 

 paper. Second, because, on the basis of my microphotographs 

 of a few specimens, some readers have determined (supposedly) 

 that I found an increase in the proportion of nuclear to cytoplas- 

 mic material. And finally, because it appears to me that the 

 study of the morphological changes which accompanied the pro- 

 tracted physiological degeneration of this culture offers a par- 

 ticularly favorable opportunity to determine exactly how great 

 the variations in cell size and nuclear size are during the life of 

 a race of Oxytricha and whether these variations are of such a 

 character as to support either of the current morphological con- 

 ceptions of cytoplasmic and nuclear relations with reference to 

 physiological degeneration. 



II. MATERIALS 



This race of Oxytricha fallax is one of several cultures of hypo- 

 trichous Infusoria which I bred some ten years ago in Professor 

 Calkins' laboratory at Columbia University. The chief object 

 of the work at that time was to repeat some of the work of Mau- 

 pas and to determine whether hypotrichous forms show cyclical 

 changes in their vitality similar to those which Calkins had 

 found to occur in his race of Paramaecium and, if such did occur, 

 to endeavor to reinvigorate the organisms by artificial stimula- 

 tion. The data at hand from this work led me to conclude that 

 "the species studied pass through periods of greater or less gen- 

 eral vitahty as measured by the rate of division. This cyclical 

 change is most prominent in the Oxytricha A culture." (The one 

 under consideration in the present study.) "The periods of de- 

 pression lead to death if the culture is subjected continuously 

 to the same environment." (p. 626). 



Subsequently I have reinvestigated the problem of the cyclical 

 character of infusorian life history in Paramaecium with special 

 reference to the effect of the environment (culture medium) and 

 have secured results which, I believe, conclusively prove that 

 this form, at least, has unUmited power of reproduction by divis- 

 ion, under favorable environmental conditions, without conjuga- 



