126 Regulation of Size in Unicellular Organisms 



rate changed whenever the size changed, and inversely 

 to it; except that the rate remained greater in the high 

 temperature for some time after the size had returned 

 to normal. 



It was noted in one instance that the smaller body 

 volume of Colpoda at a high temperature was main- 

 tained for at least one generation after transfer to a 



4 6 



Time in months 



Figure 38. Effect of temperature upon the mean body length in a clone of 

 Paramecium caudatum. Frequent subcultures were made, and kept at the 

 temperatures indicated. (Data of Jollos, '13 and '21). 



lower temperature (Adolph, '29). In subsequent gen- 

 erations the adult size of the body enlarged. On pass- 

 ing from the lower temperature to the higher, the 

 smaller size was attained very speedily, for the organ- 

 isms which were in process of growth at the time of 

 transfer ceased assimilating and underwent fission at 

 an early age. 



Assimilation rates. Evidently a variety of adjust- 

 ments may be made by diverse species and clones of 

 ciliates in response to temperature changes. A useful 

 picture of the adjustments may be based on the fact 



