44 THEORIES ON THE ABSORPTION OF NITROGEN 



difficulty which suggested the preparation of pure cultures 

 of bacteria. The first attempt at artificial cultures was made 

 by Nobbe and Hiltner and put on the market in 1890 under 

 the name of nitragine. This 7iitragine was composed of a 

 mixture of germs collected from various species of Legu- 

 minoscc in order that it might meet a number of different 

 requirements, but the trials made were inconclusive. 



Hiltner prepared other more virulent cultures. Until 

 1898 thev were cultivated on gelatine by the Institute of 

 Agricultural Botany at Munich, and afterwards by Dr. 

 Kuhn's Laboratory of Biochemistry. The preparation is 

 to-day sold in bottles for treating from about one-half to 

 two acres. 



The Swedish stations have carried out trials with these 

 products and have always found them to be inferior to the 

 method of inoculation by actual soil. 



Moore, of Washington, has made a preparation of what 

 is termed nUro-cuUure. In experiments on a large scale 

 this product was found to evaporate rapidly and to lose its 

 power. 



Professor Bottomley, of London, manufactured a similar 

 kind of mixture which is known to the trade as nifro- 

 bacterine. 



M. de Feilitzen has carried out numerous experiments 

 at Flahult and the experimental station of Jonkoping with 

 nitragine, nilro-hacterine, and inoculation by actual soil. 



M. Grandeau, who has commented on these experiments 

 in the paper L' Agriculture Pratique, gives the following 

 figures for the resulting crops : — 



Check plot, not inoculated ... ... ... 8,700 kilos. 



Plot inoculated with nitro-bacterine ... ... 7,loo ,, 



„ ,, nitragine ... ... ... 5,600 ,, 



,, ,, soil ... .. ... 43,700 ,, 



The yields w-ere thus lower where the two preparations 

 of bacteria were employed. 



M. Grandeau also calls our attention to the fact that 



