FEB2S!oip''" 
AMERICAN '^'-- Mu. 
JOURNAL OF BOTANY 
Vol. V January, 191 8 No. i 
THE INFLUENCE OF ILLUMINATING GAS AND ITS CON- 
STITUENTS ON CERTAIN BACTERIA AND FUNGI* 
C. A. LUDWIG 
INTRODUCTION 
It has been known ever since the observations of Girardin (6) 
in 1854 that certain phanerogams are susceptible to injury by the 
presence of illuminating gas in the soil or air. Since then consider- 
able work has been done in both Europe and America on the question 
and on the allied one of the toxicity of smoke. One of the outstanding 
results of the later work has been a determination of the large role 
played by ethylene in the results observed and of the exceedingly 
small amount of ethylene which is necessary to bring about the re- 
actions. It has been found, for instance, that the almost infinites- 
imally small amount of one part of ethylene in 2,000,000 parts of air 
causes closing of carnation flowers in 12 hours (i) and that the even 
smaller ratio of one part in 10,000,000 parts causes nastic curvatures 
in castor-bean seedlings (i). 
With the bacteria and fungi, however, there have not been reported 
thus far any cases where such remarkable sensitiveness to the chem- 
ically more inert organic gases has been exhibited. In fact, very 
little has been done with these gases in this field; and, in most cases 
reported, gases were used in the pure condition, very few or no at- 
tempts having been made to determine the lower limit, of toxicity. 
It became, therefore, a matter of considerable scientific interest and 
some practical importance as affecting laboratory practice to deter- 
mine as nearly as possible the lower limit of toxicity of illuminating 
* Publication No. 167 from the Botanical Department of the University of 
Michigan. 
I 
