External Factors and Size 



127 



that adult body size is the quotient of assimilation rate 

 and fission rate. A smaller size obviously means that 

 fission rate increased relatively more than assimila- 

 tion rate. The consequences to the population, ex- 

 pressed as rates of growth at various temperatures, 

 may thus be calculated from the mean sizes and fission 

 rates which have been measured, as in table 10. In 



Table 10. 



Comparison of the Rates of Multiplication and of Increase in Bulk 

 at Three Different Temperatures. Colpoda, Clone A. (From 



Adolph, '29) 



this particular clone of Colpoda it follows from the 

 measurements of fission rate and of adult size that as- 

 similation rate per individual is very little increased by 

 temperature compared with fission rate. A change of 

 ten degrees in temperature multiplies the assimilation 

 rate 1.2 times and the fission rate 2.3 times. 



The conception might be formulated that assimila- 

 tion is limited by some physical process such as the 

 rate of beat of cilia, while fission rate is governed by 

 a chemical process. Since mechanisms of assimila- 



