SOIL-INOCULATION 427 



produced within the bacteria cells are diffused through 

 the cell-wall and absorbed by the plant. 



In a recent report, De Rossi states that Pseudo- 

 munas radicicola is not the causative agent in the 

 fixation of nitrogen in the nodules of leguminous 

 plants, and that he has isolated other bacteria that 

 do possess this property. These bacteria produce the 

 Y and T forms in artificial media, which is in itself an 

 indication of their identity with the bacteria concerned 

 in nitrogen-fixation. De Rossi's work may also explain 

 why what was formerly considered to be one form 

 of bacterium, Pseudomonas radicicola, common to 

 all leguminous plants, is not capable of inoculating 

 one species of legume when transferred from another. 

 It may be that there are a number of different forms, 

 each adapted to certain species of legumes. 



290. Soil-inoculation for legumes. The possibility 

 of securing a better growth of leguminous crops on 

 soils not having previously grown such a crop success- 

 full}', was conceived immediately following the dis- 

 covery of the nitrogen-fixing bacteria. Extensive 

 experiments showed the practicability of inoculating 

 land for a certain leguminous crop by spreading upon 

 its surface soil from a field on which the same crop is 

 successfully growing. It is manifestly much better 

 to apply the organisms or a certain species of legume 

 from a field having grown the same species than to 

 attempt to use organisms from another species of le- 

 gume. The fact that soil-inoculation by means of soil 

 from other fields may possibly transmit weed seeds 

 and fungous diseases, and also necessitates the trans- 



