200 Agricultural Bacteriology. 



In some cases this specific character does not obtain. 

 For example the organisms inhabiting the ordinary 

 sweet clover are able to infect alfalfa but not the com- 

 mon red or white clovers. It is thus necessary to see 

 that the soil contains the right kind of bacteria, and if 

 they are not present naturally in the soil, it must be in- 

 oculated with them. 



Kinds of legumes. There are many thousands of 

 legumes both wild and cultivated, varying in size from 

 tiny plants to large trees, all of which bear nodules on 

 the roots. In the native flora of every type of soil are 

 to be found representatives of this group of plants. The 

 ordinary beggar-weed, the sensitive plant, and the wild 

 lupines are some of the native legumes. All of the clov- 

 ers, red, crimson, and white, the sweet clovers, both white 

 and yellow, alfalfa, all of the peas, such as garden, sweet, 

 field, and cowpeas, the various kinds of beans, soy beans, 

 lupines, vetches and serradella, and the pea-nut are 

 among the most important of the cultivated legumes. 



The legumes are found growing on all types of soils, 

 in marshy soils, in sand and clay, in those that contain 

 much lime and in those free from it. All types, how- 

 ever, bear nodules, so the bacteria capable of developing 

 under these conditions are wide spread and abundant. 



Form and appearance of nodules. The nodules vary 

 in size and appearance depending on the species of plant. 

 Those on the clovers are very small, about the size of a 

 large pin head, and oval in form, with a smooth surface. 

 The alfalfa nodules are much like those of clover but 

 have a tendency to grow in finger-like clusters. The 

 nodules of beans are round, rough on the surface, and 

 much larger than those on clovers, some times reaching 

 the size of a large cherry. The nodules on peas are very 



