146 SOILS 



pies that lend their silent servants to alfalfa with no 

 noticeable resentment on the part of the bacteria. It is 

 not the rule, however. Born within their caste, it seems 

 out of the question for bacteria to escape the borders that 

 enclose them. It is no doubt true that these many kinds 

 of bacteria each legume has its own came from a com- 

 mon ancestry, when all legumes were served alike, and 

 before wide differences became manifest. 



As an example of this, we have only to refer to the 

 experience of all alfalfa growers in those sections of the 

 country where this crop has been introduced only re- 

 cently. Although some other legume may have been 

 grown repeatedly on the same soil, no assistance seems 

 to be afforded the alfalfa plant until first there is supplied 

 to the soil the special bacteria that have grown accus- 

 tomed to this legume. 



Bacteria may act slowly at first. It often happens, also, 

 that when legumes are grown in a soil for the first time, 

 neither they nor bacteria do very effective work. Either 

 they have not got acquainted sufficiently to work in 

 harmony, or too few bacteria are present in the soil. I 

 have observed this a number of times, and with several 

 legumes. The first season but little is done : the roots 

 lack vigor and possess but few nodules, the stalk is 

 slender and lacks hardiness, the leaves are pale, and poor 

 health is generally manifest. In the second season a 

 change is noted: in each respect just mentioned there is 

 improvement and betterment. And often a third year, 

 even, is necessary in order to secure vigor, strength, color, 

 yield and size just as you would have them. An exam- 

 ination of the roots shows that an abundance of tubercles 

 is obtained, often, during the second season, and usually 

 by the third. Plants and bacteria now work in harmony, 

 and both prosper. 



