260 



BOTANY 



PART I 



which occur parasitically in higher plants and have the same property. 

 The best investigated among these are the various forms of Bacillus 

 radicicola, which infest the roots of Leguminosae and frequently give 

 rise to enormous numbers 

 of gall-like tubercles upon 

 them (Figs. 251, 252). 

 The Leguminosae thus 

 appear to differ from all 

 other green plants in their 



FIG. 251. A root of Vicia Faba, 

 with numerous root -tubercles. 

 (Reduced. After NOLL.) 



FIG. 252. 1, Young tubercles (1C) on a root (IF) of Vicia Faba, 

 B, large-celled tissue filled with masses of Bacteria, M, the 

 "meristem" of this. T, tracheides. (x 60.) 2, A cell of 

 the tubercle filled with thousands of Bacteria, and beside 

 it some un-infected cells, (x 320.) 3, An infected root- 

 hair containing the "infection hypha." (x 320.) U, Bacteri- 

 oids. 5, Unaltered Bacteria, (x 1200. After NOLL.) 



mode of accumulating nitrogen ( 38 ) ; this was -first established by 

 GILBERT and LAWES in England and ScHULTZ-LuPiTZ in Germany. 



The rod-shaped bacteria penetrate through the root-hairs into the cortex of the 

 roots, and there give rise to the tubercles. These tubercles become filled with 

 a bacterial mass, consisting principally of swollen and abnormally-developed 

 (hypertrophied) BACTEIUOIDS, but in part also of bacteria, which have remained 

 in their normal condition. While the bacteria live on carbohydrates and at first 



