18 



SCIENCE. 



[N. S. Vol. VII. No. 158. 



serradella had been grown. These soils, 

 which were to be used for inoculation, were 

 taken from portions of the field where the 

 roots were abundantly provided with the 

 usual nodules. The soil selected for inocu- 

 lation by these samples was sandy, poor in 

 humus and rich in lime with a gravelly sub- 

 soil. 



The inoculations which were made have 

 shown that the lupines and serradellas, 

 which, up to that time, had never been 

 developed successfully in the fields where 

 the experiments were made, in spite of 

 most careful culture, showed a remark- 

 able growth in comparison with the plots 

 which were not inoculated. The serra- 

 della which was inoculated directly with 

 the nitragin did not respond to this inocula- 

 tion, but peas inoculated with the nitragin 

 showed a remarkably luxuriant develop- 

 ment of the plants, with the formation of 

 radical nodules, in comparison with the 

 plants cultivated at the same time and not 

 inoculated. It is necessary, however, that 

 these experiments with inoculation be re- 

 peated for several years before definite con- 

 clusions in regard thereto can be drawn. 

 (I'Engrais, Vol. 12, 1897, p. 351.) 



Experience has shown that preparations 

 of nitragin do not retain their vitality in- 

 definitely and, in order to secure the best 

 results, should be used as soon as possible 

 after manufacture. It is evident also that 

 the particular source from which each 

 sample of nitragin is prepared must be 

 designated, and the farmer wishing to use 

 it as a fertilizer must purchase those varie- 

 ties which are suited to the crop he wishes 

 to grow ; otherwise, he may make the mis- 

 take of applying nitragin derived from peas 

 or beans to a clover field, or the contrary. 

 An excellent review of the methods of 

 preparing nitragin and the processes of its 

 application is given by J. Augustus Voelck- 

 er, in the Journal of the Eoyal Agi'icul- 

 tural Society of England, Vol. 7, third 



series, part 2, pp. 253 et seq. The method 

 of obtaining the pure cultures of the nitri- 

 fying bacteria is as follows: 



A plate of prepared gelatin is inoculated 

 from the nodules of the leguminous plants 

 containing the living bacteria. A second 

 plate is inoculated from one of the colonies 

 formed in the gelatin plate. This process 

 is continued until a pure cultivation is ob- 

 tained, due to one particular species of 

 nitrifying organism. 



In preparing nitragin for commercial use 

 the pure cultivation, obtained as above, is 

 placed in a bottle, holding from 8 to 10 

 ounces, containing a small quantity of agar 

 gelatin on which it is allowed to grow. 

 The bottle is sealed and the contents kept 

 in the dark. Up to the present time nitra- 

 gin has been prepared from 19 different 

 kinds of leguminous plants. Each bottle, 

 when sealed, has a difierent colored label 

 according to the kind of crop it is intended 

 for, and also the German and botanical 

 name of the plant. The contents of . a 

 single bottle are sufficient for securing the 

 inoculation on an acre and a-half of land 

 on which the crop is to be grown and are 

 sold for about 65 cents. In appearance, as 

 a rule, the bottle seems to be filled to the 

 depth of one and a-half inches with a light 

 brown jelly in which may be noticed a 

 white growth or mold. Care must be taken 

 that the temperature of the mixture be not 

 raised above blood heat and that the bottle 

 be not exposed for any length of time to 

 strong light. A moderately high tempera- 

 ture and exposure for any length of time to 

 intense light destroy the vitality of the 

 organism. 



The nitragin may be used directly on the 

 the seeds which are to be sown, which, on 

 germinating, develop radicles on which the 

 organisms grow. In the inoculation of the 

 seed the contents of the bottle of nitragin 

 are liquefied by gentle warmth and poured 

 into half a liter of lukewarm water. Any 



