20(5 MASSACHUSETTS HORTICULTURAL SOCIETY. 



possessed by some soils more tlian others, and that plants have 

 no power to do it without the assistance of bacteria, 



Mr. Moore said that for the last two or three years we had 

 heard much of bacteria destroying plants, and he was glad to know 

 that they produced some benefit to the soil. 



Professor Caldwell said that pear blight was the first instance 

 where bacteria have been connected with vegetable disease. 



Hon. Marshall P. AVilder referred to an article in the "Pro- 

 ceedings of the Twentieth Session of the American Pomological 

 Society," by Professor J. C. Arthur, in which he gives an account 

 of some experiments, going to show that pear blight is caused by 

 bacteria, and said that it might all be true. We had been taught, 

 and it seemed to him very probable, that nitrogen is very dormant 

 and ineffective until brought into contact with other substances. 

 We have long known the effect of ammonia on plants when it has 

 been washed down out of the air b^- a shower, and this is more 

 forcibly demonstrated in the greenhouse, by sj'ringing the plants 

 with a weak solution of ammonia. The proper administration of 

 heat, light, air, and water are the most important points in the 

 cultivation of plants. He was amazed to see how the professors 

 dittered in the results of their experiments in regard to nitrogen, 

 and it looked to him quite probable that these differences were due 

 to fraud. 



Professor Caldwell said that the subject of his paper today was 

 suggested by a remark, made by Mr. Moore, when he (Prof. C.) 

 read a paper on a kindred subject here last year, that plants get 

 their nitrogen in some way from the air. The subject announced 

 for today was a much broader one ; he had shown in his previous 

 paper only what plants must get from the air ; he intended now to 

 show that in every arable soil there is an immense supph' of nitro- 

 gen. The entire results of experiments on this subject must be 

 based on trustworthy chemical analysis, and he wanted to show 

 how the contradiction occurred ; it was entirely impossible to ol)tain 

 such results as those of M, Ville by fair means. Lawes and Gil- 

 bert would not have repeated their exi)erimeuts, if it had not 

 been neccssarv to demonstrate the incorrectness of M. Ville's 

 statements. 



President Walcutt said that nitrogen is the " mugwump" among 

 gases. It stands around without much to do generally, but when 

 a great occasion arises it comes in, yet it cannot be depended on 

 for a permanent alliance. 



