IJACTKIUA OF THE SOIL 



root. Stain the sections in 1 per cent acetic acid in which arc 

 dissolved equal portions of fnchsin and methyl violet. Wash the 

 sections briefly with wate^ and make microscopic examination. 



FIG. 30. Increased growth of beans due to inoculation with B. radicicola 



Plant on the left grown in uninoculated soil ; plant on the right grown in inoculated 

 soil. (After Ferguson) 



Look especially for the " infection threads " extending through 

 the cortical cells of the root. The protoplasm of the root cells 

 and tubercle cells should appear blue, and the bacteria red. 



