Inoculation by Cultures 229 



injurious to the bacteria, which pass out from the in- 

 terior of the seed to the seed-coat. The bacteria brought 

 into contact with these poisonous secretions of the seed 

 are destroyed or weakened and are no longer able to 

 infect the young legumes. In order to obviate this 

 latter difficulty, it was proposed to soak the seed in 

 water for soriie hours, thus getting rid of the poisonous 

 secretions, and thein to inoculate the swelled seed. There 

 was, however, a practical objection to this method, — 

 the inconvenience in planting partly germinated seed. 

 Subsequent inquiry showed that the poisonous secre- 

 tions produced in the seed could be made harmless to 

 the bacteria by mixing the cultures, preparatory to 

 inoculation, in a weak solution of salts or in skimmed 

 milk, instead of water. 



Artificial cultures. — A gradual improvement has thus 

 been made in the character of artificial cultures and has 

 led, within the last two or three years, to very gratifying 

 returns from their use in Germany. The keen disap- 

 pointment which followed the failure of nitragin in 

 1896, 1897 and 1898, cast discredit on artificial cultures, 

 and the farmers in Europe went back to the cumbersome 

 but more certain legume-earth method. The so-called 

 New nitragin, slowly evolved by the efforts, largely, 

 of Hiltner ahd his associates, is restoring the confidence 

 in artificial cultures. 



Extensive experiments with such cultures, conducted 

 throughout Germany, and especially Bavaria, have 

 yielded very promising results within the last three 

 years. A positive increase from inoculation has been 

 obtained, not only on soils that had never borne legumes, 



