250 Bacteria in Relation to Country Life 



there is evidenced by its being referred to as the "mort- 

 gage lifter." Its early cultivation in New Jersey dates 

 back to about the same time. The acreage devoted to 

 it was greatly increased in 1891 to 1894, owing to the 

 investigations of the experiment station. It has been 

 used in these states for the improvement of unculti- 

 vated unproductive soils, as a green-manuring crop in 

 the regular rotations and as a cover-crop in orchards. 



The information thus gathered concerning this crop 

 serves to throw an interesting light on the bacterial 

 relations. involved in the gathering of nitrogen from the 

 air, as well as in the decomposition of the green-manure 

 in thei'sOil. "The experiments conducted by the Delaware 

 station showed that crimson clover completes its work 

 of gathering nitrogen at a much earlier date on soils that 

 have previously borne it than on those to which it is new. 



This circumstance may be explained partly by the 

 assumption that on the older soils the crimson clover 

 derives a larger proportion of its nitrogen from the soil 

 itself rather than from the atmosphere. Now, since 

 such soils contain considerable quantities of available 

 nitrogen, the clover plants will take it up and develop 

 rapidly in the. early part of the growing season. This 

 explanation is only partial, however, for, as a matter 

 of fact, the older soils contain greater numbers of nodule- 

 bacteria, and possibly also more virulent modifications 

 of thefee organisms. The early formation of numerous 

 tubercles allows the plants to gather large amounts of 

 nitrogen, in a comparatively short time, an advantage 

 not possessed by crimson clover on new soils. 



The differences thus indicated lead to variations 



