D. W. Cutler 



437 



It may be concluded therefore that the capacity of sand, soil and clay 

 for retaining flagellates and amoebae is independent of the condition of 

 the organisms, whether they are in the cystic or active form, but varies 

 with the size, as experiments with ciliates demonstrate. 



2700 



■2400- 



2000- 



1600 



S 1200- 



800- 



400 



1600 2000 2400 



Number of organisms per c.c. left in solution 

 Fig. 1. Showing the number of amoebae and flagellates withdrawn from suspensions of 

 varying strengths by the different types of solid matter. A = clay, B = untreated and 

 partially sterilised soil, C = ignited soil, D =fine sand, E =coarse sand. Since complete 

 retention occurs when the number of organisms added is less than the capacity of the 

 solid matter, the first part of each of the above curves is coincident with the ordinate. 

 The numbers of organisms are given in thousands. 



Experitnents with varying amounts of solid tnatter. 



In these experiments 2 c.c. of suspension was added to weights of 

 solid matter varying from 1-0-1 gram. Again the results demonstrate 

 that solid matter has a specific capacity for withdrawing a definite 



Joum. of Agric. Sci. ix 29 



