NITROGEN : WHY AND WHERE CROPS MUST GET IT. 205 



these methods of transfer of nitrogen from the air to the plant, 

 whose limits have not yet been determined. 



Therefore we can unhesitatinglj' admit that our crops may get a 

 portion of their nitrogen from the air, as appears to be plainly 

 shown by many experiments and much experience ; and we can do 

 this without being in the least degree forced to admit that plants 

 can assimilate free nitrogen, and without being forced to cast a 

 shadow of a doubt on the reliability of the researches of Boussin- 

 gault and of Lawes, Gilbert, and Pugh — investigators to whom 

 the science and the art of agriculture owe such a \evy large share 

 of the progress that has been made in the last thirty years, and 

 whose trustworthiness we cannot afford to call in question. 



Discussion. 



President Walcott expressed the thanks of the Society to Pro- 

 fessor Caldwell, for the conclusive paper which he had read. 



John B. Moore was called on and said he was glad that Pro- 

 fessor Caldwell had demonstrated the correctness of the opinion 

 which had been expressed here in previous years, that plants 

 possess the power of in some way absorbing nitrogen from the air. 

 He was surprised at the view of the lecturer, that M. Ville's 

 experiments were not trustworthy ; his book caused a great deal 

 of thought and did good. He thought that others than chemists 

 could perform such experiments as those of M. Ville, and that, 

 with his own practical knowledge of cultivation, he could apply 

 the results of experiments as well or better than chemists. 



William H. Hunt said that he was in Paris when M. Ville was 

 giving a course of lectures, and he attended one where the 

 audience consisted of two persons besides himself, in a room that 

 would accommodate three or four hundred persons. The courses 

 were free, and the lectures on interesting subjects by good authori- 

 ties were well attended. 



President Walcott said that formerly- monsters were considered 

 thq worst enemies of the human race, but now minute organisms 

 are. But these germs have themselves so many enemies that it is 

 difficult to cultivate them when wanted as subjects of study. The 

 results of experiments of Professor Schlosing on the power of 

 bacteria to produce nitrification agree with those of Berthelot, 

 quoted by Professor Caldwell. It was shown that the function is 



