342 POPULAR SCIENCE MONTHLY. 



any considerable morphological change in root tissues. Nor is it at 

 all highly probable that the anticipated morphological and biological 

 adaptive relationship would be permanent or auto-transmissible to 

 other generations of the new host. It is probable that the relationship 

 would be temporary only. It may be quite marked at the period of 

 seed germination and then gradually decline more or less rapidly. 



The time required to change or modify the rhizobia sufficiently to 

 induce them to develop in or upon the roots of gramineous and other 

 non-leguminous plants must be determined experimentally, and this 

 is the most essential part of the experimentation. It is reasonable to 

 assume that considerable time will be required, one year, and perhaps 

 even a much longer period. It will also be necessary to experiment 

 with various media in order to determine which particular culture 

 medium will produce the desired changes most effectively and most 

 rapidly. Present indications are that acid media are not specially 

 indicated as was once supposed, though they induce rapid and very 

 marked morphological changes in the rhizobia. 



The agricultural conditions of Europe are quite different from 

 those of the United States. In the plan of research suggested, the 

 interests of the American farmer are of prime importance. Wheat 

 and corn are the two staple farm products of the central, eastern and 

 western states, and in the above discussion these have been primarily 

 in mind. Later researches may be extended to other American farm 

 products, as cotton, tobacco, potatoes, etc. Opportunity must be had 

 to make frequent field experiments or tests along with the purely labo- 

 ratory experimentation. 



The successful outcome of the research will result in inestimable 

 value to farmers. The modified microbic soil fertilizer will serve 

 essentially as a living fertilizer; it will do away with the use of the 

 well-known guano, manure and other chemical fertilizers, which are 

 applied at great labor and expense. It will also do away with the 

 need of crop rotation, which to the agriculturist is a costly process, 

 as it necessarily reduces the cultivation of the staple farm product. 

 It is hoped that the increase in crop yield, resulting from the use of 

 the microbic soil fertilizer, will amount to from 5 per cent, to even 50 

 per cent., depending primarily upon the condition of the soil. Eich 

 soil naturally requires no fertilizer of any kind. 



The following is a brief summary of the essential points discussed 

 in this paper with special reference to the plan of research outline: 



1. Bacteria of the root nodules of leguminous plants (rhizobia) 

 have the power of assimilating free nitrogen independent of their inti- 

 mate biologic association with the host plant. 



2. Ehizobia, especially the species known as R. mutdbile, found in 

 the root nodules of the majority of leguminous plants, are highly poly- 



