6o THE SPIRIT OF THE SOIL 



4. In many cases hastened maturing of plants, 

 thus allowing the earlier marketing of produce with 

 enhanced value. 



The fact that it was possible in certain conditions 

 to obtain such results made it plain that it was 

 worth while to continue working at the problem. 

 As will be seen in later chapters, the further work 

 done has led to results that at the time were un- 

 suspected, and that are far more important than 

 were dreamt of at the time. Before considering 

 them, however, it will be well to conclude this 

 chapter with a short account in view of modern 

 knowledge of the Bacillus radicicola in its relation to 

 leguminous plants. 



The B. radicicola is a small rod-shaped organism 

 that is found widely distributed in nature. For 

 some reason, as yet unexplained, it is able to attack 

 the roots of the leguminous plants. It forces its way 

 into the delicate root hairs of the growing legumes, 

 and penetrates into the interior of the root branches. 

 When once it has effected an entrance it increases in 

 size and changes its shape, appearing sometimes as 

 irregular rods and at others as V or Y shaped 

 organisms. For its growth it requires food in the 

 form of sugar and mineral salts, and these it takes 

 from the roots of the leguminous plants which it has 

 invaded. There can, as will be seen presently, be 

 little doubt but that the leguminous plant resists 

 the entry of the bacillus. The bacillus, however, 

 forces its way in, demanding, as it were, rights of 

 partnership, and once it has established itself and 

 secured food and shelter, it offers to its host in return 

 Nitrogen that it can take from the air, and give to 



