551 



The formation of nitrates in the process of nitrification, S. 

 Winogradsky (Ann. de VInstitut Fafiteur, 5 [I'^^Ul), p. 577; aha. in 

 Chcm. Ztf/., 15 {1S91), rep., p. 345). — The author dra^vs the following- con- 

 clusions from his more recent studies of the organisms of nitrification. 

 The product of nitrification in normal soils is always nitrates exclusively, 

 a fact long believed to be true. The oxidation of the nitrites to nitrates is 

 not diminished in the least by the presence of even considerable quanti- 

 ties of ammonia, but takes place immediately on their formation. There 

 can be no doubt, he asserts, that in the soil as well as in liquid cultures 

 the pure nitrous ferment produces nitrites exclusively; and that when 

 these nitrites are once formed they can not be further acted upon and 

 oxidized by the nitrous ferment, i. e. the nitrite organisms can not 

 produce nitrates. The nitrites thus formed in the soil are constant 

 compounds in the absence of the nitric ferment, whether or not the 

 common soil microbes be present. But if the nitric and the nitrous 

 ferments are both brought into sterilized soil provided with ammonium 

 salts, nitrates result, and only occasional traces of nitrites can be 

 detected. The nitrites formed are oxidized immediately to nitrates, no 

 matter how much ammonia is present which the nitrous ferments have 

 not attacked . 



These conclusions agree in the main with and confirm Warington's 

 results and views. Eegarding the morphology of the nitrifying organ- 

 isms there is some difference of opinion. Winogradsky describes the 

 nitric ferment as consisting- of long, pear-shaped rods not over 0.5// 

 long and usually about one half to two thirds as broad; and the nitrous 

 ferment as fioni four to five times as large as the nitric organism and 

 more nearly elliptical in form. 



On the fixation of free nitrogen by plants, T. Schlbsing, jr., and 

 E. Laurent {Compt. rend., 113 {1891), pp. 776-77.9).— A report on experi- 

 ments in continuation of those described in Comptes rendus, 111 (1S90), 

 p. 750 (see Experiment Station Eecord, vol. in, p. 116). Both the " direct" 

 and "indirect" methods of determining the acquisition of nitrogen were 

 employed, as in the previous experiments. In these later experiments, 

 however, natural soils were used, which were treated as follows: To 

 a poor, sandy soil was added lime and a mixture of richer soils (gar- 

 den soil and soil on which grain, clover, lupines, and beans had been 

 grown). A mineral solution was used as a fertilizer. After the seeds 

 of various plants had been sown a liquid mixture of distilled water and 

 the soils above mentioned was poured over the surface of the soil in the 

 pots. Two series of experiments w^ere made. In the first, which 

 extended from May to August, the plants grown were Jerusalem arti- 

 choke, oats, peas, and tobacco. There were also pots w^hich contained no 

 plants. After a time the soil in all the pots was more or less covered 

 with green plants of a low order, especially certain species of mosses 

 and algfe. The results showed that in every case gaseous nitrogen had 



