INOCULATION AND NITROGEN. 227 



rootlet. This nodule is filled witli these bacteria. 

 Nodules are not all alike; some look like little seeds, 

 some like bunches of grapes. They vary in size and 

 shape very much. Nodules on alfalfa plants are 

 rather smaller usually than alfalfa seeds. They 

 exist only on the root hairs. Evidently these bac- 

 teria prefer the new fresh roots. 



The Work of Bacteria. — What do the bacteria do 

 for the plant! In some way they digest nitrogen 

 and assimilate it. In some way the plant gets it. 

 How? We do not know that. Maybe they die and 

 decay and the plant absorbs them. Maybe the plant 

 assimilates part of them before they get old enough 

 to die. Anyway we know that they get hold of the 

 nitrogen that exists in the air and that comes down 

 into the soil through its pores, get hold of it, use- it 

 and give it to the plants. That is the mirade that 

 lets life exist on this world of ours. A happy chance 1 

 Yes, or a thought of God. It is certain that were it 

 not for this "chance," human life, and animal life as 

 well, would ultimately perish from the face of the 

 earth. On such tiny beings as these bacteria does all 

 life on the world hang for its ultimate existence. 

 Thoug'htful men have long felt alarm over the state 

 of the world as far as the food supply of the people 

 was concerned, all because of this very drain of nitro- 

 gen from the soils by crop growing. Dr. Cyril G-. 

 Hopkins says : 



But a short time ago Sir William Crookes predicted that 

 within thirty or forty years England would experience a wheat 

 famine, due to the exhaustion of nitrogen in the soil, that would 

 be appalling in its effect; and Prof. Bela Korasey's warnings to 



