270 
Journal of Agricultural Research 
Vol. XXIV, No. 3 
The results show that the 3deld increases with an increase in the 
concentration of dextrose in the media. An average of the three peri¬ 
odical analyses for each medium gives a yield of 15.7 per cent for the 
0.6 per cent dextrose solution, 20.2 per cent for the i.i per cent solution, 
and 25.9 per cent for the 1.5 per cent solution. 
'The total nitrogen content of each medium at the completion of the 
experiment reveals the fact that nitrogen fixation occurred at the rate 
of 16.1 mgm. of nitrogen per gram of dextrose in the 0.6 per cent dex¬ 
trose solution, 17.0 mgm. of nitrogen per gram of dextrose in the i.i per 
cent dextrose solution and 17.3 mgm. of nitrogen per gram of dextrose 
in the 1.5 per cent dextrose medium. 
The dextrose disappeared rapidly from all solutions, being entirely 
consumed by the sixth day. 
UTILIZATION OF MOLASSES 
The waste molasses from a sugar factory should offer an available 
source of energy for Azotobacter. Hence an experiment was con¬ 
ducted in which molasses was substituted for dextrose in the medium, 
and the azofication ability of cultures was determined in this medium. 
The medium contained i per cent molasses, or by analysis 0.51 per cent 
of invert sugar. The quantity of nitrogen fixed per 100 cc. of medium 
for five cultures aerated for six days was as follows: 
Mgm. 
I B. 
a B. 
SB 
13 B, 
332.. 
1-5 
3-3 
3*3 
3-4 
3-6 
The results show an average net gain of 3.03 mgm. of nitrogen per 
gram of molasses. A gram of molasses represents only 0.51 per cent of 
invert sugar, giving, therefore, a rate of fixation of 6.06 mgm. of nitrogen 
per gram of invert sugar. 
To determine the yield from molasses, 250 cc. of the i per cent molasses 
medium was inoculated with culture No. 19 and aerated for four days 
at 30®C. The medium was analyzed for sugar, total nitrogen, and 
yield. The results are given in Table V. 
Tabi,® V .—Yields nitrogen fixed, and sugar fermented from molasses 
Sugar per loo cc. 
Nitrogen per loo cc. 
Weight per 50 cc. 
Yield. 
Control. 
Culture. 
Gross. 
Control. 
Net. 
Gross. 
Control. 
Net. 
Gm. 
0.50 
Trace. 
Mfftn. 
10. S3 
Mgm. 
8.15 
Mgm. 
2.38 
Gm. 
/ 0.0799 
|l 0 - 093 S 
Gm. 
0.0063 
0.0149 
Gm. 
\ 0.0761 
Per cent. 
30.44 
The total nitrogen content of different samples of molasses has varied 
froni about 6 to 12 mgm. per gram of molasses. This nitrogen appears 
to be in a soluble form, since lead acetate fails to precipitate it. On the 
other hand, if a lead acetate solution is added to an Azotobacter culture 
cultivated in this molasses medium, a heavy membraneous precipitate 
forms. An experiment, therefore, was arranged to ascertain whether 
