156 THE SPIRIT OF THE SOIL 



warned of the extreme difficulty of field experiments. 

 It was pointed out to me that, even when every care 

 was taken to give the whole of a field identical treat- 

 ment, such a field, if divided into plots, would yield 

 returns from certain plots that would vary by as 

 much as 50 or i oo per cent, from the mean, and that 

 long-continued experiment, therefore, was necessary 

 before the results claimed for soil inoculation could 

 be accepted. Professor Bottomley, I was told very 

 truly, was an enthusiast with more laboratory than 

 field experience, and might have been misled by 

 results apparently due to the bacteria, but due in 

 reality to other causes of which he had no know- 

 ledge. Facts and figures were quoted to me showing 

 how frequently in the past generalizations have been 

 made by men of science in connection with agri- 

 culture on insufficient experiments, and that the 

 result has been disappointment and the discrediting 

 of science among practical farmers. 



Experience has shown that there was real wisdom 

 underlying these criticisms. From the standpoint 

 of the practical man nitrobacterine was a failure, 

 because it was not realized that certain conditions 

 were essential for its successful application. Scien- 

 tifically, however, it was a success, as is proved by the 

 fact that after seven years of experiment the Ameri- 

 can Board of Agriculture is distributing a similar pre- 

 paration to farmers and recommending its use. 



As against the criticisms I heard, there were the 

 results that were obtained. The laboratory experi- 

 ments proved conclusively that under controlled 

 conditions nitrobacterine gave results of an order 



