INFLUENCE OF ILLUMINATING GAS ON BACTERIA AND FUNGI 1 1 
and 25 percent gas, 3 transfers in 50 percent, 5 transfers in 85 percent, 
and 9 transfers in pure gas. In the unsuccessful trials with pure gas 
in the later work the organism always developed on the slant after 
being exposed to the air, although sometimes appearing in separate 
colonies instead of a streak, as if most of the inoculating bacteria had 
been killed. When success was attained in cultivating the organism in 
pure gas it then seemed likely that the bacillus had in some way 
developed the ability to grow under those conditions which were at 
first inhibitory; but this hypothesis was found to be untenable when 
trial was made by inoculating from a line which had been cultivated 
in the air only, for these cultures developed just as well as the ones 
which had been carried in gas for several transfers. These apparently 
contradictory results seemed quite unexplainable except on the assump- 
tion of a change in the composition of the gas, and it was thought at 
the time that no significant change had taken place. Later, knowledge 
was obtained of the variation in the gas concentration which has 
already been noted. Upon comparison it was found that the success- 
ful cultures of the organism began about Feb. i, 1917, at the time the 
change was made to pure coal gas instead of the mixture of coal and 
water gas. The significant change in the composition of the gas would 
seem to have been the drop from about 12 or 13 percent to 7 or 8 
percent of carbon monoxide. It should be remarked, however, as 
will be shown later, that neither of these concentrations of CO is of 
much significance if the rest of the mixture be atmospheric air. In 
fact, the tolerance of the organism to CO-air mixtures is so great that 
one would not expect a difference of only 5 or 6 percent in the con- 
centration to exert any marked effect. It is also worthy of note that 
the first failure to grow in the gas occurred during the first period 
when the gas consisted of pure coal gas and had the lower carbon 
monoxide content. The results, therefore, are even yet unexplain- 
able with the data at hand. 
Bacillus Kieliensis. — ^This organism grows vigorously, reaching a 
maximum in 3 to 4 days, and has a very brilliant red color with a 
strong greenish metallic or coppery sheen on the surface. After the 
colony has reached its maximum the sheen gradually disappears, 
the colony becomes brickish red, and the pigment often diffuses more 
or less into the medium. This color responds readily to cultural 
conditions and so furnishes a sensitive index for detecting disturbances 
of the life processes. Its alterations are so numerous and complicated, 
