LEGUMINOUS CROPS. 



15 



that these swellings were the storehouses for nitrogenous 

 compounds — these compounds being subsequently used up 

 in the ripening of the seed. But it has been shown by- 

 subsequent research that Tschirch's idea is erroneous, and 

 that these root-nodules are pathological or disease struc- 

 tures, caused by a microscopic fungus whose spores are, at 

 times, found in cultivated soils. 



During the seasons of 1886 and 1887, field and garden 

 beans were attacked, more or less, by a fungus which 



^&«a.- 



Fig. 3. — Roots of Bkoad Beans, 

 (Kicia/aba) infested with a fungas causiog nodular ont-growths. 



caused nodular out-growths upon the roots, and thereby 

 caused great injury to the crop (Fig. 3). 



In the neighbourhood of Etton, near Peterborough, the 

 crops of winter beans were, during 1887, a complete 

 failure. Mr. G. W. Edgson (a well-known farmer) of 

 Etton sent the author a number of these bean plants for 

 inspection. They were about seven inches long. Mr. 

 Edgson wrote as follows : " The roots of the winter beans, 

 you will find, are cove/ed with small boils, which appear 

 to be living upon the plant, and have kept the bean 

 plants in the stage you now see them. For the last few 



