MYCODOMATIA OF THE LEGUMINOSAE. 103 



decay and break-up of the tubercles, reach the soil ready to 

 bring about new infections. 



The great importance of the tubercles of Leguminosae is 

 that the plants bearing them are capable of taking up free 

 nitrogen from the atmosphere and utilizing it, while without 

 the tubercles they could not do so.^ If Leguminosae be grown 

 in soil rich in nitrogenous food-substances, the tubercles are 

 not so well developed. 



According to Schneider,^ the host-plant under the influence 

 of the Khizdbmm produces cellulose tubes, which become filled 

 with the fungus. According to Beyerink,^ these tubes consist 

 of bacterial slime secreted by the Bhizobium. The epidermal 

 tissue of the tubercles consists of a loose layer of cork with 

 many intercellular spaces ; this arrangement is stated by Frank* 

 to facilitate the usual transpiration.^ 



'Hellriegel u. Wilfarth, Berichte d. deiUsch. boian. Ges., 18S9; also Zeitschri/t 

 f. cl. Bilhenzueker-Inditstrie, 1888. 



^ Ber. d. devtsch. botan. Ges., 1894, p. 11. 



'^GenircUbl. f. Bacterologie u. Parasitenhunde, 1894. 



"Ben d. deutsch. botan. Ges., 1892. 



^ Schneider (Bulletin of the Torrey Club, 1892), gives a short account of 

 American Rhizobia, and refers to the chief works on this subject. (Edit.) 



