NITRIFICATION IN ARABLE SOIL. 355 



iiitroduetioii of these feriiieiits (luring' tlie course of the exi)eriineiit. 

 The phiuts were inclosed in glass vessels, and the air supplied to them 

 was conducted through glycerin in order to remove all dust which 

 might carry in the nitrifying germs. Under these conditions corn, 

 beans, barley, horse beans, and hemp attained a normal development 

 iu a soil in which no nitrates were present, and their growth can only be 

 attributed to the influence of the ammonia salts used as a fertilizer. 



Breal, of the Laboratory of Vegetable Physiology of the Museum of 

 Paris, has recently reported a very simple method of demonstrating 

 the assimilation of ammonia salts. He took from a meadow a tuft of 

 Poa <(nnua, washed the roots carefully, and placed it in water iu a tlask 

 of dark glass or one which was wrapped with iiaper in order to pre- 

 vent the growth of alg;e. After a few days the grass developed 

 new white roots, which were covered with abundant root hairs. The 

 old roots were cut oft and sufficient mineral matter for the development 

 of the roots was introduced into the water in the flask along Avitli a 

 certain amount of ammonia salt. At the beginning the solution gave a 

 strong reaction with Nessler's reagent, but after 24 hours this reagent 

 did not indicate the presence of ammonia.' In this case the plant 

 thrived in a solution containing 1 part in 10,000 of sulphate of ammonia. 



In view of the fact that ammonia introduced into the soil is readily 

 transformed into nitrates, it maybe maintained that these experiments 

 are only of physiological interest, and that since ammonia resulting 

 from the decomposition of nitrogenous organic nuitterof the soil passes 

 rapidly to the state of nitrates, the question of principal importance is 

 to know how the ammonia is produced. Tlie subject of the assimila- 

 tion of ammonia com})Ouiids assumes greater importance, however, 

 w^hen we remember that nitrates are found in the soil of neither mead- 

 ows nor forests, and that undoubtedly plants which grow on these 

 soils derive their nitrogen from ammonia. 



Certain of the decomposition products of the nitrogenous substances 

 of the soil appear to have a composition analogous to that of the 

 amids. Their decomposition under the influence of chemical forces at 

 100° (J. and above is limited by the presence of ammonia salts, as 

 determined by the laws of dissociation.^ In the soil at ordinary tem- 

 peratures nitrogenous materials are transformed by fermentation. 



For the investigation of this subject Miint/ and Condon prepared 2 

 lots of the same soil as nearly alike as possible. One was allowed to 

 remain at ordinary temperatures, the other was heated to 120° C. for 

 several hours to sterilize it. The 2 samples were exposed to the air 

 under like conditions, after having the ammonia in them determined. 

 After 42 hours the lot which had not been heated had formed IS.I parts 

 jier 1,000 of ammonia; after lOo hours the quantity had increased to 50,4 

 parts; while during the same period the amount of ammonia remained 



' Anu. AgTon., 19, ]>. 279. -A. Hebert. Ann. A,i>roii., 15, p. 35,">, 



