HOFFMANN: SOIL PRODUCTIVITY. 



99 



Table IX. — Influence of the extracts of variously cropped soils upon the rule of multi 

 plication of one of the denitrifying organisms. Number of bacteria per cc. of extract. 



Table X. — Influence of the extracts of variously cropped soils upon the rate of multi- 

 plication of Sarcina lutea. Number of bacteria per cc. of extract. 



1 Univ. Sci. Hull., Vol. IN, No. 7 



