16 FARM SPIES 



'"How do you do?' said the bacterium to the 

 vetch-plant. 



'" Not very well/ answered vetch. ' I cannot get 

 enough nitrogen. You know that every meal I eat 

 I must have potash, phosphoric acid, and nitrogen ; 

 I can get enough of the first two, but I am starving 

 for nitrogen, and so I feel very bad. Nitrogen, 

 you know, is hard to keep in the soil, and as it 

 costs so much, farmers are not willing to supply 

 enough of it.' 



"'That is very funny/ answered the bacterium; 

 'with me it is just the other way. I have all- the 

 nitrogen I need because I have a very cheap way of 

 making it, but I cannot get enough potash and phos- 

 phoric acid, and as I have to have them on my table 

 as well as you, I am starving. 7 



" Dr. Science then stepped forward and asked the 

 bacterium, ' You say you have an easy way for mak- 

 ing nitrogen ; will you explain it to me ? ' 



" ' With pleasure/ the bacterium replied. ' Three- 

 fourths of the air is nitrogen, and God has given 

 me the power to draw on this vast storehouse and 

 change it so that it can be eaten by plants. 7 



"'Wait 'a minute, Mr. Bacterium/ said Dr. 

 Science; 'would it be possible for you two to get 

 together and trade?' 



"'I have an idea/ exclaimed the vetch-plant; 

 'we can live together ; the bacterium can live on my 



