200 TILLEES OF THE GEOUND CHAP. 



up the barberry plants. Unfortunately, however, 

 other botanists have shown that, though the fungus 

 generally needs to spend part of the year on the 

 barberry, yet in some countries, as in Australia, it 

 seems able to do without the barberry. Even in 

 parts of England at least sometimes it can do 

 without that plant, perhaps using some other plant 

 instead. But if we do not know yet how rust may 

 be prevented altogether, we at least know enough 

 now to see in what direction help is to be sought. 



CHAPTEE XVII 



PLANT FOOD AND THE UTILISATION OF THE SOIL 



OF all the improvements which man's toil and 

 patience have produced in the growing of plants, 

 perhaps in some ways the most important is the 

 improvement of methods, especially of methods of 

 treating the soil. It seems clear at least that, in 

 the immediate future, the greatest progress in con- 

 nection with agriculture will be made along the 

 lines of the proper utilisation of the soil in 

 learning how to make it fertile and how to keep 

 it so. 



The whole story of the way in which man has 



