INFLUENCE OF ILLUMINATING GAS ON BACTERIA AND FUNGI 21 
Bacillus pyocyaneus. — B. pyocyaneus grew well in all of the con- 
centrations used, but with an almost indistinguishable retardation 
in percentages of 45 percent or above. This, however, had disappeared 
by the end of 3 days. 
Bacillus Kieliensis.- — The development of B. Kieliensis in methane 
was good throughout, but was slightly less vigorous in the greatest 
concentrations used. It was practically impossible, moreover, tO' 
determine the exact concentration at which the first inhibition could 
be said to occur. The color was also affected comparatively little, 
though it seemed in some cases to extend as low as 10 percent 
(corrected) . 
Bacterium steward and Sarcina lutea. — Contrary to expectations, 
these organisms were practically unchecked in all the percentages 
used except the very highest, about 60 percent (corrected) ; and even 
here the growth was good. 
Oidium lactis.- — The development of 0. lactis was practically un- 
checked throughout the series of methane exposures. In the highest 
percentages, 50 percent to 65 percent (corrected), there was a ten- 
dency for the mycelium to have a white, velvety appearance instead 
of the more typically appressed, water-soaked appearance. 
Cryptococcus Ludwigi. — The growth of this pink yeast was good 
in all concentrations of methane. It was usually slightly pale at 
45 percent (corrected), somewhat pale and retarded at times at 50 
percent (corrected), and distinctly pale and usually somewhat retarded 
at 65 percent (corrected). 
Penicillium stoloniferum. — The growth of P. stoloniferum was 
slightly checked at concentrations of 45 percent to 65 percent (cor- 
rected). 
As can be seen from the foregoing data, the toxic effects of methane 
on the organisms up to 65 percent of the gas are very mild and are 
certainly not of a character to suggest that 30 to 35 percent of methane 
in the illuminating gas used could be responsible for the inhibiting 
effect which illuminating gas exerts. 
3. Ethylene 
Production and Purification of the Gas 
The ethylene used in these experiments was produced by heating 
95 percent alcohol with c.p. sulphuric acid. It was passed through 
