672 THE NODULE ORGANISM OF THE LEGUMINOS.E, 



carbonaceous media poor in nitrogen, and was of «u large a size 

 that experiments were made in order to ascertain if this could fix 

 free atmospheric nitrogen. The experiments were negati\e: the 

 l)lanks showed the same amount of nitrogen as the cultures. 

 This organism appeared sometimes as a streptococcus, and some- 

 times as a chain of fat bacteria, the individual cells measuring 

 about 3 fj. long and about 2 fx broad. A culture in lupin extract 

 that had stood for two months showed a collection of spores. On 

 solid media these developed into smaller compact rods withi 

 rounded ends, and this appearance, together with the culture- 

 characteristics obtained from the original organism, identified the- 

 bacillus as £ac. megatheriuvt . The recognition of this organism, 

 which, if not identical with, is very closely allied to, the alinit 

 bacillus, Bac. Elleuhachii a, which is claimed to assist the cei'eals- 

 in collecting nitrogen from the air, induced the trial of a mixed 

 culture of this bacillus with Rhizohium in order to see if these- 

 organisms growing together could fix atmospheric nitrogen in 

 artificial culture. The mixed culture grew most luxuriantly to 

 form a syrupy fluid, which was in great contrast to the thinner 

 cultures of the separate organisms. There was no gain of nitrogen, 

 however, by the cultui'es. A second set received an additional 

 quantity of glucose after reaching the syrupj^ stage, but still there 

 was no gain. Cover-glass prepai-ations of the eleven days' syrupy 

 culture showed the rhizobia staining strongl}' as if in extremel}-: 

 vigorous condition. A number of short empty capsule tubes were 

 dimly visible. The growth of megatherium was restricted; spores 

 occurred here and there, and there were a few short chains of 

 coccus forms. The small coccus-like buds, as well as the mature 

 forms of Rhizohram, were frequently seen adhering to these 

 chains. There were a few large oval cells which contained one 

 or two rhizobia; the cells apparently consisted of a stain -absorlnng 

 plasma, and probably were huge capsules. Yellow masses of b\'e- 

 product also occurred; these recalled the masses after seen in the 

 nodule cells. Bearing in mind that the nodules are rich in starch, 

 it seems possible that Bac. viegatherium. may functionate as a 

 starch dissolver, and in this wav assist the nutrition of Rhizobium.. 



