302 THE STRUCTURE OF RHIZOBIUM LEGUMINOSARUM. 



media that a certain amount of slime would be formed. Much 

 might be learnt regarding the true inner structure of the cells by 

 training them to increase their zoogloea slime as I have done 

 with the nodule-former. 



Rhizobium leguminosarum is not the only bacterium which has 

 a composite structure. I have mentioned some pathogenic 

 bacteria, and in view of the similar morphology and chemical 

 nature of the slime (capsule) of Vibrio denitrificans, there can be 

 little doubt that it has the same structure. The rosette-forming 

 Bacterium radiobacter produces a slime under certain conditions, 

 and when stained in the manner that I have recommended, it is 

 seen to have a vacuolated appearance. The chromatin appears 

 in transverse bands in the majority of cases, but frequently these 

 are divided, and just as often a large terminal coccus can be seen. 

 The division of the hand is sometimes pronounced and the halves 

 are rounded, in short, they are cocci. Frequently the large 

 coccus shows a transverse clear space or line. It is probable that 

 the bands are cocci pressed out of shape by a non-staining cell 

 plasma, and that the true coccoid shape results when the surface 

 pressure is reduced. 



We thus see that Bad. radiobacter has some structural affinity 

 with Rhizobium leguminosarum, and probably many more 

 bacteria may be similarly constructed. 



