THE NITRATE PROBLEM 9 



private chimney-pots of householders in the great 

 cities. 



There remains one great source of nitrates and a 

 great army of workers adapted from the beginning 

 of time for the fundamental work of nitrate pro- 

 duction, fitted for that work and that work alone, 

 an army of workers that require only the intelligent 

 co-operation of the farmer and the man of science 

 efficiently to perform their duties the bacteria of 

 the soil. It is the purpose of this book to show how 

 an English man of science working in an English 

 laboratory has set out to solve the problem of 

 facilitating the work of the soil bacteria, how the 

 experiments carried out in laboratory, hothouse 

 and field, all go to prove that the bacteria of the 

 soil intelligently applied cause a growth of crops 

 heavier than that obtained by manures owing to 

 the steady supply of nitrogen that they furnish to 

 the plants, and owing to the potash and phosphate 

 that they render available, and, lastly, how in the 

 course of his researches he has been forced to believe 

 in the existence and potency of certain mysterious 

 accessory food substances produced through the 

 action of the bacteria, which bring about a develop- 

 ment of plant life unparalleled by any manure 

 hitherto known, whether natural or artificial. 



I have no wish that these statements should be 

 accepted on the ipse dixit of the workers themselves, 

 or of those who have conducted field experiments. 

 In the following pages the attempt will be made to 

 describe simply the laboratory results of the last 

 eight years' work at the Botanical Laboratories of 



