CHAPTER VI 



SIZE IN RELATION TO MULTIPLICATION 



RATE 



Is reproduction merely an expression of growth, as 

 Johannes Miiller ('40) postulated? In unicellular 

 organisms does reproduction occur every time a cer- 

 tain size is attained, or are conditions other than in- 

 crease of size required? This latter should be a simple 

 question for which to find an affirmative answer, but 

 a hard one to prove negatively, for a single case of re- 

 production without growth in the absence of any 

 change in external conditions would indicate the pos- 

 sible independence of these two factors. 



1 . Growth as a Prerequisite to Reproduction 



The uniformity of adult size, which has been already 

 evaluated, indicates that growth ordinarily proceeds 

 to a fixed extent between two reproductions. When 

 growth is modified in various ways, is reproduction 

 also affected? 



Starvation. Reproduction is usually inhibited in 

 individuals that are starved during any considerable 

 portion of their period of individual growth. This was 

 illustrated particularly well in the starvation experi- 

 ments with Paramecium recorded by Estabrook ('10). 

 Jickeli ('02) found some exceptions to this generality, 

 and put forth the contrary hypothesis that fission is 

 stimulated by hunger. 



In many instances, as that cited in figure 14 above, 

 refeeding after starvation allows a resumption of 

 growth. In such cases reproduction has been much 

 delayed as compared with fed controls. In these cases, 



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