86 



MARY H. CHAMBERS. 



TABLE VII. 



C. MIXED CULTURE, POWERS AND POWERS. Daily Division Averaged for Six 



Day Periods. 



This was a rich culture containing many infusoria, and a high 

 percentage of bacteria. In these individuals the rate showed 

 little increase above the average. 



TABLE VIII. 



D. WILD RACE. Daily Division Averaged For Six Day Periods. 



The wild race of Paramecia had to undergo the greatest change. 

 It thrived as the others on the rich diet of malted milk, but the 

 experimental lines decreased exceedingly in division rate. 



In the comparative study of these races it must be concluded 

 that, (i) yeast stimulates growth as indicated by the rate of 

 division, and (2) ground yeast is more favorable as food than 

 whole yeast. 



The physiological condition of the individual must be taken 

 into consideration. For example in races A and B there was a 

 higher rate of division than in races C and D. The latter ones 

 had been in rich cultures before they were subjected to the ex- 

 periment. Such a series also reveals the great variation in the 

 rate for different individuals under the control conditions. 

 For example, in Table V the variation of the control is 4.5, in 

 Table VI., 3.2, in Table VII., 1.3 and Table VIII., 0.34. Al- 

 though every effort was made to keep the conditions the same 

 there is evidence of great variation. 



