BY R. GREIG-SMITH. 301 



As these granules become more or less reddish when coloured 

 by some blue stains, e.g., polychrome methylene blue, they are 

 said to be metachromatic. Granules staining similarly are met 

 with generally in the bacteria, yeasts, moulds, algse, &c, but they 

 appear to be of the nature of a reserve material which has been 

 called "volutin" by Arthur Meyer. On account of the meta- 

 chromatic character of the Babes-Ernst bodies, Guilliermond* 

 assumes that they consist of volutin. 



Although the round granules of Rhizobium may simulate 

 volutin granules in their staining properties, yet in view of these 

 observations regarding the structure of the nodule-former, it is 

 clear that they are not reserve material, Rhizobium leguminosarum 

 is a compound micro-organism and consists of cocci, micrococci or 

 diplococci, the chromatin of which may be swollen or condensed, 

 within a tubular, straight or branching rod or capsule, f 



There are some points of resemblance between Rhizobium 

 leguminosarum, Bac. diphtheria} and Bac. tuberculosis. Under 

 certain conditions they exhibit branching forms and the cells 

 contain granules of dense chromatin. The granules of Rhizobium, 

 which I have shown to be condensed coccoid structures, are 

 stained reddish (purple) by Leishman's modification of the 

 Romanowsky stain, and in this respect appear to be identical with 

 the Babes-Ernst granules of the diphtheria bacillus. Bac. tuber- 

 culosis, under certain conditions, shows an irregular staining and 

 has avacuolated appearance, supposed to be caused by a plasmolysis 

 of the bacterial protoplasm, and even terminal coccoid structures 

 (so-called spores) may be observed. J It is true that the free 

 coccoid forms have not been observed with these bacteria, but 

 this maybe a question of medium and of the nature of the capsule. 

 The so-called spores are most clearly seen when the bacteria are 

 grown upon media with a vegetable basis, and it is upon such 



*Bull. del'Inst.Past.iv.(1906) 145. 



f A name is required for the capsular rod. That of sporangium raises the 

 inference that the contents are spores, and as they are clearly micrococci or 

 diplococci, the name is misleading. 



% Meier, Cent, fur Bakt. Ref.xxxvi. (1905) 606. 



