PARAMOECIUM POSSESSING EXTRA VACUOLES 



305 



2. Medium filtered from culture from which paramoecia were obtained to conduct 

 these experiments. Culttire was about one week old 



3. Hay infusion freshly made up 



NUMBER OF DIVISIONS 



5.6 



EXPERIMENT B 



Two vacuoles, 82 per cent 

 Three vacuoles, 18 per cent 



4. Medium filtered from culture containing many animals which had been allowed 

 to evaporate (concentrate) and had been refilled with fresh hay infusion four 

 times. The concentration of the metabolic products present was doubtless quite 

 high and the culture had a very strong odor. At the time this experiment was 

 started fresh infusion had been added to the culture about twenty-four hours 



NUMBER OP DIVISIONS 



4.5 



EXPERIMENT B 



Two vacuoles, 37.5 per cent 

 Three vacuoles, 50 per cent 

 Four vacuoles, 12.5 per cent 



The foregoing data point strongly, I think, to the fact that 

 rapidity of division plays a very important r61e in influencing 

 the production of the extra vacuoles. Apparently one of the 

 chief requirements for the production of the extra vacuoles for 

 which this race possesses the potentiality is sufficient length of 

 time between divisions. When the rate of division is rapid the 

 two-vacuoled animals tend to predominate as illustrated by 

 Experiment A, 2; and Experiment B, 3. With a slower rate of 

 multiplication there appear more three and four-vacuoled para- 

 moecia as the results of Experiments A, 1 and B, 1 and 2 show. 

 Moreover, in old cultures where the division rate is low two- 

 vacuoled animals are very scarce when not absolutely lacking. 

 While there is some slight variation in the results of the corre- 

 sponding sets of experiments I am not at present inclined to 



