[Vol. 6, 1919] 



44 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



Explanation of Plate 



plate 1 



Photomicrographs of Azotobacter chroococcum, X 1170. Culture 



No. 5 from liquid medium, others from agar slants. 



Fig. 1. A 12-hour-old culture stained with dilute aqueous 

 methylene blue. 



Fig. 2. Same, stained with carbol gentian violet. 



Fig. 3. A 60-hour-old culture, methylene blue. 



Fig. 4. Same, carbol gentian violet. 



Fig. 5. A 5-day-old culture, methylene blue. 



Fig, 6. A 15-day-old culture, carbol gentian violet. 



