D. Ward Cutler and L. M. Crump 



23 



together quite well. This would often occur, but in many cases the corre- 

 lation will break down if the intervals are long between the successive 

 counts. Doubtless many of the numerous contradictory results in the 

 earlier literature can be ascribed to this cause. 



It would be premature to discuss the relation between the numbers 

 of active and cystic amoebae, or the reason why, after a period of de- 

 pression, the total number of amoebae should suddenly greatly increase. 



45 



40 



35 



Fig. 7. 



17 14 21 28 



Rainfall and ground temperature from February 9 — March 8, 1920. 



The answers to such questions are to be found in a knowledge of the 

 life histories and physiology of these protozoa, which at present we do 

 not possess. 



It is hoped to continue the daily counts for a year to obtain data, 

 which, with those yielded by pure culture study, may throw light on 

 the principles underlying the daily fluctuations. 



