444 Observations on Soil Protozoa 



are independent of the concentration of the suspension, the time of 

 action, or whether the suspension contains cysts or active forms of the 

 amoebae and flagellates investigated. Also the action is the same when 

 the experiment is performed with a suspension of living or dead organisms. 

 5. Experiments with the ciliate — Colpoda cucullus — show that 

 coarse sand per gram retains 27,000 per c.c. ; fine sand per gram 185,000 

 per c.c; soil and partially sterilised soil 280,000 per c.c; ignited soil 

 270,000 per c.c. and clay 450,000 per c.c 



REFERENCES. 



1. Martin, C. H. and Lewin, K. R., Joiirn. Agric. Science, 7, 1915. 



2. GooDEY, T., Roy. Soc. Proc, 88, 191.5. 



3. KoPELOFF, N., and Coleman, D. A., Soil Science, 3, 1917. 



4. KoPELOFF, X., Lint, H. C, and Coleman, D. A., Cent. J. Bald. Bd 45, 1916. 



5. Russell, E. J. and Goldincj, J., Jonrn. Agric. Science, 5, 1912. 



6. Russell, E. J., and Appleyaeu, A., Journ. Agric. Science, 7, 1915 



{Received 21st June, 1919.) 



CAMBKIDGE : PRINTED BY J. B. PEACE, M.A., AT THE DNIVERSITY PRESS. 



