22 
C. A. LUDWIG 
wash bottles containing water, sodium hydroxide solution and c.p. 
sulphuric acid respectively. In the earlier work it was stored in a 
gasometer over water until required for use. The results were later 
checked by another experiment made with gas stored in a mercury 
seal gasometer. The following is the analysis of the gas used in this 
last experiment: 
Acid gases, CO2, SO2, etc 7.2% 
C„H2. 81.0% 
The first nine of the following organisms were tested in 0.4 percent, 
4-5 percent, 20 percent, 40 percent, 50 percent, 60 percent, 85 percent, 
and 100 percent (uncorrected values), except as otherwise stated, of 
ethylene. The concentrations, corrected according to analysis, which 
were used in verifying the results were 4 percent, 8 percent, 20 percent, 
40 percent, 60 percent, and 80 percent. The percentages mentioned 
in connection with the first 9 species in the following notes are the 
corrected values unless otherwise stated. 
Bacillus suhtilis. — ^With B. suUilis there was no abnormality of 
colony type and no great checking of development in any concentra- 
tion. There was none at all below 40 percent, and it was doubtful at 
that percentage. At 60 percent, however, it was unmistakable al- 
though not great. 
Bacillus pyocyaneus. — Owing to the semi-translucent nature of 
the colony of B. pyocyaneus it was difficult to detect small differ- 
ences in development, so that the lower limit for retardation as 
given may be somewhat too high. There was very little inhibiting 
effect exhibited, however; and the type of colony was not altered. 
The lowest concentration at which a retarding effect could be clearly 
distinguished was 60 percent, with a possibility that a very slight 
inhibition occurred sometimes at 40 percent. 
Bacillus Kieliensis. There was little inhibiting effect exerted by 
ethylene on B. Kieliensis The organism grew vigorously in all the 
concentrations, and was quite often as vigorous as in air up to a con- 
centration of 85 percent (uncorrected), but usually retardation could 
be detected at 40 percent and color variations at 20 percent or even 
sometimes at 8 percent. 
O2 
CO2 
Difference (N. + Ho + CH4) 
.3% 
•3% (or perhaps none) 
11.2% 
Effect on the Different Organisms 
