VERMONT AGRICULTURAL REPORT. 103 



which have to do with the nitrogen gathering - properties of 

 the leguminous plants, like clover, peas, beans and the like, 

 and the nitrifying and denitrifying bacteria which have to do 

 with the fitting and unfitting of nitrogen for plant uses. 



The farmer long ago observed that the growth of clover 

 bettered instead of impoverished a soil. It remained, how- 

 ever, for the investigator to search out the reason for this 

 phenomenon. It was found that certain classes of bacteria 

 have the habit of locating themselves upon or rather within 

 the roots of the pod-bearing plants, of forming thereon little 

 enlargements called tubercles or nodules, and of living 

 therein. This copartnership is established for their mutual 

 benefit, each plant helps the other. The minute bacterium is 

 housed and fed by its host, the clover plant, and it pays rent 

 in the form of nitrogen. The clover or pea or bean plant 

 builds up the bulk of this structure from the water and car- 

 bonic acid of the soil and air. It leaves to its little renter, 

 however, the gathering of the nitrogen for making protein, 

 the tissue builder, from a source which it alone can reach. 

 So far as is now known, none but the leguminous plants 

 afford house room to this class of plant life, and none but they 

 are able to draw on the inexhaustible bank of the atmosphere 

 for their nitrogen supply. 



The relation of bacteria to nitrification is also important 

 in this connection. Plants can absorb their food only when 

 it is dissolved ; and a bit of dried meat or blood, a grain of 

 cotton seed meal, or a fragment of manure is useless as a fer- 

 tilizer unless it become available. The nitrogen these contain 

 is insoluble, but nature, through its agents, the bacteria, gets 

 to work upon it and transforms it through various stages into 

 soluble forms, fitted for plant needs. The germs which bring 

 this about are known as nitrifying bacteria. Just as there 

 are in the world of large things men whose pleasure it seems 

 to be to thwart the work of others and to work mischief and 

 destruction, so there are present in every soil de-nitrifying 

 germs, which undo the work of the nitrifiers, which destroy 

 the food thus made ready for plant uses, which reduce it 

 again to nitrogen and oxygen, which are useless in that shape. 



It is important that the farmer appreciate the point al- 

 ready mentioned and here reiterated that usually the nitrogen 

 fixers and nitrogen fitters, the useful germs, "thrive best in 

 well drained, well tilled, well aerated soil; and that the nitro- 

 gen robbers, the destroying germs, lurk in damp soils, where 

 air is relatively lacking. Drainage and tillage, therefore, 

 serve to develop the one and to hinder the other. 



4. Tillage sends the roots rambling: The root system of 

 a plant is as important as is leaf growth. A plant which is 



