juneis. I9IS Azotobacter Chroococcum ■ 235 



A summary of the results of the tests to distinguish between meta- 

 chromatic and chromatic granules is given in Table I. 



Table I. — Summary of results of the tests for ynetachromatic and chromatic granules O: 



" -I- signifies a coloration; — , a discoloration. 



6 Methylene blue (i:io)= i part of methylene-blue saturated solution added to lo parts of water. 



As can be seen from Table I, there is no doubt that metachromatic 

 or, as A. Meyer (12) terms them, "volutin" granules were found. 



DISCUSSION OF RESULTS OF THE EXPERIMENTS 



Since, according to the tests performed, the metachromatic nature of 

 the granules is assured, their action in the cell will be studied to ascer- 

 tain whether they have a role in the metabolism which confirms the 

 microchemical investigations. 



As we know, Meyer (12) considered metachromatic granules as reserve 

 foods, while MacCallum and Carlier, according to Guilliermond (7, p. 

 199), considered them as "zymogenic granules." Although the writer 

 does not believe a conclusion as to whether the granules of the writer 

 are reserves or zymogens can be reached in the present paper, he thinks 

 that by presenting some points of the question a working hypothesis 

 may be sketched for future worl^. 



One of the main points for consideration is the disposition of these 

 granules in the cell — i. e., to determine whether a regular disposition 

 takes place at some time in the life of the cell or whether the granules 

 have no special setting in the organized unit. 



To begin with, the drawings furnished by Mencl (11) will be studied. 

 In nearly all cases in which a reticulated structure is to be seen, the 

 granules are placed on the juncture of the net meshes or also in the center 

 of the meshes themselves. As to the regularity of distribution in the 

 cell, these granules present none, because, as Mencl himself states, all 

 stadia, from fine scattered points to large globules, are to be found. 

 Considering the large globules as the maximum development of the 

 material composing them, the most advanced stage morphologically, 

 they should be expected to occupy a uniform place in the fully developed 



