58 The Story of the Bacteria 



covered that these root nodules are made up 

 largely of rod-like and irregular-shaped bac- 

 teria (Fig. 7). Several forms of these can 

 now be cultivated artificially, and it has been 

 found that they have the power of seizing 

 upon atmospheric nitrogen and working it 



over into available form 

 for the uses of their 

 host. These bacteria 

 get into the rootlets 

 of the leguminous plant 

 and grow there as par- 

 asites, not at first al- 

 together welcomed it 

 would seem. But pres- 

 ently they begin to 

 satisfy the intense ni- 

 trogen hunger of the 

 clover, alfalfa, peas, and beans, and thus the 

 happy family lives on in mutual helpfulness. 

 So at last, down in this borderland of life has 

 been discovered the key to untold riches for the 

 farmer. For he now knows the importance of 

 root nodules and their bacteria, and can trans- 

 fer them from field to field, or he can get from 



FIG. 7. NODULE BACTERIA 



These irregular shaped 

 bacteria were artificially 

 cultivated from the nodules 

 on the roots of leguminous 

 plants. 



