1 84 



THE FIRST BOOK OF FARMING 



age sized bacteria placed side by side to measure 

 one inch. 



These little germs make their homes in the roots 

 of the legumes, causing the root to enlarge at cer- 

 tain points and form tubercles or nodules (Figs. 

 34 and 35). 



Carefully dig up a root of clover, cpwpea, soy 

 bean or other legume and wash the soil from it. 

 You will find numbers of the little tubercles or 

 nodules. On the clover they will be about the size 

 of a pin head or a little larger. On the soy bean 

 they will be nearly as large as the beans. These 

 nodules are filled with colonies or families of bac- 

 teria which take the free nitrogen from the air 

 which penetrates the soil and give it over to the 

 plant in return for house rent and starch or other 

 food they may have taken from the plant. 



In an experiment at Cornell University Agricul- 

 tural Experiment Station, in 1896, clover seeds were 

 sown August ist, and the plants were dug Novem- 

 ber 4th, three months and four days after the seeds 

 were sown. The clovers were then weighed and 

 tested and the following results were obtained: 



