94 



THE STRUGGLE FOR EXISTENCE 



influences Paramecium very strongly, and that every individual of the 

 former occupies a place available for 5.5 Paramecia. With our 

 technique of cultivation it is difficult to decide on what causes this 

 depends. As a supposition only one can point to food consumption. 



to 



6t>- 



>/0 



%20 





I* 



n 



P. cau datum separate/y 

 n+d=7? 



o 



d*r v 



P. cat/datum in mixed population. 



2 



S myii/us separately 



K+d'is.s 



S.myiilus in mixed population 



\ 



a 



o I Z 3 t/ 



Days 



Fig. 18. The growth in number of individuals of Paramecium caudatum and 

 Stylonychia mytilus cultivated separately and in the mixed population, d 

 denotes lower asymptote. From Gause ('34b). 



(6) We have but to change slightly the conditions of cultivation 

 and we shall obtain entirely different results. Figure 19 represents 

 the growth of populations of the same species on a dense "oaten 

 medium with sediment" sown with various wild bacteria. Here 



