COMPETITION FOR COMMON FOOD IN PROTOZOA 



107 



the expense of a certain level of food resources which is a constant one 

 in all "half-loop" experiments and may be taken as unity, P. aurelia 

 growing separately produces a biomass equal to 105 volume units, 

 and P. caudatum 64 such units. Therefore, one unit of volume of 

 P. caudatum consumes ^ T = 0.01562 of food, and one unit of volume 



Zoo 



P.aure/fa 



Separately 



Jn mixed population 



P. caudatum 



19 



Days 



Fig. 25. The growth of the "volume" in Paramecium caudatum and Para- 

 mecium aurelia cultivated separately and in the mixed population on the 

 buffered medium with the "one-loop" concentration of bacteria. From Gause 

 C34d). 



of P. aurelia -jfe = 0.00952. In other words, one unit of volume of 

 P. caudatum consumes 1.64 times as much food as P. aurelia, and 

 the food consumption of one unit of volume in the latter species con- 

 stitutes but 0.61 of that of P. caudatum. These coefficients enable 

 us to recalculate the volume of one species into an equivalent in 

 respect to the food consumption volume of another species. 



