295 



THE STRUCTURE OF RHIZOBIUM LEGUMINOSAKUM. 



By R. Greig-Smith, D.Sc, Macleay Bacteriologist to the 

 Society. 



(Plates xxi.-xxii.) 



From the appearances presented by Rhizobium legiiminosarum 

 when grown in a peptone-glucose fluid medium, I concluded in a 

 former paper* that it was a yeast, chiefly because vacuoles and 

 budding forms were the prominent features. I have not, however, 

 been able to confirm this view, for although vacuolation and small 

 terminal cocci are undoubtedly present, we can interpret these 

 characters otherwise when we take into consideration other 

 phenomena that are manifest upon growing and staining the cells 

 under more favourable conditions. 



During the investigation of the production of slime by Rhizo- 

 bium, recorded in the preceding paper, cover-glass preparations 

 were made from time to time to determine the influence of 

 nutrients, &c, upon the formation of bacteroids, i.e., branching 

 forms of the micro-organism, and in some cases special experiments 

 were made to discover the action of certain methods of nutrition. 



Suchtingf in a critical study of the nodule bacteria reviews the 

 work of numerous investigators, some of whom, e.g., Beijerinck, 

 Laurent, Stutzer and Hiltner, found that bacteroids could be 

 obtained on solid media, while others, e.g., Prazmowski, Neumann 

 and Siichting himself, found that they could not. 



I have grown the cells upon solid media and have undoubtedly 

 obtained bacteroidal forms, as can be seen from the plates which 

 accompany this paper. But at the same time I have found a 



* These Proceedings, 1899, 653. 

 + Centr. fur Bakt. 2te. Abt. xi. (1903) 381. 



