External Factors and Size 



129 



salts, and in it one or another of three flagellates, from 

 clonal cultures, were fed to them. The differences in 

 body size were considerable, as shown in figure 39. 

 Particularly between individuals feeding upon the two 

 green flagellates Gonium and Chlorogonium was the 



Figure 39. Influence of temperature and of quality of food, upon mean 

 adult body size in Colpoda. G were feeding on Gonium, CI -IV on Chloro- 

 gonium, and PI-II on Polytoma (From Adolph, '29). 



contrast striking; at either 16.7° or 26.4° the Colpodae 

 had twice the body volumes upon the former food as 

 upon the latter food. In this instance there was little 

 chance of chemical differences other than those of the 

 food, for both these flagellate species were grown in 

 the absence of organic substances; they obtained their 



