138 



THE STRUGGLE FOR EXISTENCE 



(compare the first and second cycles on Figure 39, i and 2 ). This 

 problem, however, requires further investigations. 



(2) It is interesting to compare our data with some observations 



A/ z —P.bunaria (predator) 



N, — S.pomSz (p r e.y) 



no 



no 



o Vo So 



1^2.- Pzurelia (predator) -=9 



Fig. 39. "Classical" periodic fluctuations in a mixed population of Para- 

 mecium bursaria and Schizosaccharomyces pombe in the usual (1) and in the 

 relative form (2). (3) Periodic fluctuations in a population of Paramecium 

 aurelia and Saccharomyces exiguus in the relative form. According to Gause, 

 '35b. 



made at the Rothamsted Station (Cutler, '23, Russell, '27) which also 

 attracted the attention of Nikolson ('33). There is reason to suspect 

 that the fluctuations in the numbers of soil organisms observed by- 

 Cutler and referred to by Russell are interspecific oscillations. "Bac- 



