826 
Journal of Agricultural Research voi. xxiii, no. io 
They cultivated yeast in a synthetic medium containing no possible source 
of vitamine and obtained a good growth. They concluded that the yeast 
must either synthesize its own vitamine or grow without such “bios.” 
Nelson, Fulmer, and Cessna (6) likewise grew yeast in a synthetic medium 
and concluded that yeast could synthesize its own vitamine. 
The controversy over the vitamine needs of yeast stimulated the 
author's interest in the Azotobacter cell. The ability of this organism to 
grow rapidly and vigorously in a synthetic medium containing no nitro¬ 
gen is familiar. Such a medium contains no possible source of vita- 
mines, if care is exercised in its preparation. Media thus prepared in 
this laboratory have always afforded a vigorous growth of Azotobacter 
when placed under favorable conditions for growth. It is assumed, there¬ 
fore, that the Azotobacter organism is not dependent upon such growth- 
promoting factors for development or that it is capable of synthesizing 
vitamines for its needs. 
Under these conditions it would be of interest to learn whether this 
growth resulting from Azotobacter development contained any vitamines. 
Their presence would thus indicate the ability of Azotobacter to synthe¬ 
size growth promoting substances. 
Preliminary feeding experiments on white rats, with a diet in which the 
water-soluble B vitamine w T as replaced by dried Azotobacter cells, revealed 
the possible presence of a growth promoting substance. In this experi¬ 
ment the Azotobacter was grown on dextrose Ashby agar placed in large 
wooden trays to give a large surface exposure. The growth was scraped 
from the surface of the agar after two days’ incubation at 30° C. and air 
dried. 
Three white rats were fed on the following diet: 
Per cent. 
Starch. 58 
Casein. 20 
Lard. 10 
Butter. 5 
Ash. 3 
Agar. 2 
Azotobacter. 2 
The beneficial effects of the feed are shown in figure 1: 
Pig. i.— Average gain for three rats fed Azotobacter. Control rats died. 
Three rats fed on the same diet minus the Azotobactor failed to gain 
in weight, developed the characteristic sore eyes, and soon died. 
These results indicated the possibility of the presence of a food accessory 
f actor for rats fed on a diet deficient in water-soluble B. However, needed 
