INOCULATION AND NITROGEN. 227 
rootlet. This nodule is filled with 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 miracle that 
lets life exist on this world of ours. A happy chance? 
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. 
Thoughtful 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 
