DESCRIPTION OF PLATE. 



(All figures reduced one-half.) 



Fig. I. The fermentation tube as used in the foregoing investigations. 

 a. The bulb freely exposed to the air filtering through the cotton 

 wool plug ; d, the closed branch ; c, the connecting tube ; d, the 

 foot. The tube used in the foregoing investigations requires 

 about 25 cc. of bouillon, 20 of which belong to the closed branch. 

 The line .Ty divides the aerobic from the anaerobic portion of the 

 tube. This line is very sharply drawn by aerobic bacteria. The 

 turbidity on the one side bounds absolute clearness on the other. 

 In facultative anaerobic cultures there exists at this line a sud- 

 den marked change from turbidity to mere cloudiness. 



Fig. 2-8. Graphic representation of gas production by different bacteria 

 in different sugar solutions. The short lines on the left margin 

 of the tube show the rapidity with which gas accumulates and 

 serve as a means of comparing different types. The volume of 

 CO, and H found at the close of the period of gas production is 

 indicated by brackets on the right margin of the tube. 



Fig. 2. B. coll communis in glucose bouillon. 



Fig. 3. The same bacillus in lactose bouillon. 



Fig. 4. The same bacillus in saccharose bouillon. 



Fig. 5. B. cloaccs in glucose or saccharose bouillon. 



Fig. 6. B. cloaccs in lactose bouillon. 



Fig. 7. Saccharomyces cerevisics (isolated from compressed yeast) in 

 glucose or saccharose bouillon. 



Fig. 8. B. coli in peptone bouillon. The gas formed indicates the 

 presence of considerable muscle glucose. 



