ELISHA MlTCHBlvL SCIENTIFIC SOCIETY. 19 



Nitrification could be started or stopped at pleasure 

 and was clearly seen to be due to the life action of 

 these micro-org-anisms. The observations of Schloes- 

 ing* and Muntz were soon followed by the publication 

 of the experiments carri-ed out in the Rothamsted 

 laboratory by R. Warington (J. Chem. Soc. 1878, 44). 

 In addition to confirming the previous experiments of 

 Schloesing and Muntz, Waring ton added many proofs 

 establishing the ferment theory and showing- its rela- 

 tion to nitrification. The results of his experiments 

 extending" over a period of about fifteen years (J, Chem. 

 Soc. 1878, 1884, 1885, 1889, 1891) are published with 

 all the minute details. And it is to the labors of War- 

 ing-ton more than to any one else that we owe our pres- 

 ent knowledg-e of the nature and results of the life ac- 

 tion of these microscopic org*anisms. The fact that 

 they were really lower forms of life was not generally 

 accepted, thoug^h the chain of evidence establishing this 

 theory now seems to be complete. They possess all 

 the attributes of org-anized life requiring" a suitable 

 temperature for their development and suitable food for 

 their existence. The most favorable temperature is 

 about lOQo F; above 120° or below 40° they are rend- 

 ered inactive, and are destroyed at 212°. The pres- 

 ence of org"anic matter and phosphates are essential. 

 They are destroyed by the action of disinfectants, in- 

 secticides, and the presence of any considerable amount 

 of alkalinity is detrimental to their growth, Just as 

 calcium carbonate or wood ashes were required in 

 n'.tre heaps so it, too, is necessary for the g-rowth. 



These org^anisms are found much more abundant in 

 the surface layers cf the soil, a fact which confirms 

 observations, long- known to be true, that production of 

 nitrates was mainly confined to the surface. Even in 



