I 
THE EFFECT OF TOBACCO SMOKE AND OF METHYL 
IODIDE VAPOR ON THE GROWTH OF CERTAIN 
MICROORGANISMS* 
C. A. LUDWIG 
During the winter of 1 916- '17 the writer of this paper was engaged 
in a study of the effect of illuminating gas and its constituents on 
certain bacteria and fungi (3) and as an accompaniment to this work 
carried out some similar experiments with tobacco smoke and methyl 
iodide vapor. Since there is no immediate opportunity to carry these 
experiments further it has seemed desirable to report briefly on them, 
although the results attained are necessarily quite preliminary in 
character. The work was done under the direction of Prof. F. C. 
Newcombe, for whose help the writer wishes here to extend thanks. 
Tobacco Smoke 
Not much experimental work has been reported showing the effect 
of smoke on bacteria or fungi, although Tassinari (5) showed as long 
ago as 1888 that tobacco smoke has a retarding effect on a number of 
pathogenic and non-pathogenic bacteria when they are exposed to the 
smoke before being put into the sterile nutrient medium. More 
recently Molisch (4) has shown that tobacco smoke will stop the move- 
ments of Chromatium vinosum (Ehrenb.) Winogradsky, Beggiatoa 
sp., and Spirillum sp.; and that it will retard the growth of Phycomyces 
nitens. 
It is quite impossible, of course, to get any accurate idea as to the 
composition of any sample of smoke without making an analysis of 
the sample. A number of papers have been written, however, having 
an especial bearing on a qualitative determination of the compounds 
present. No attempt will be made here to summarize this work 
further than to enumerate some of the compounds found and thus to 
call attention to the complexity of the mixture called smoke. Vohl 
and Eulenberg (7) reported a series of hydrocarbons of the benzene 
series or one analogous to it, and in addition formic, propionic, butyric, 
* Publication No. 169 from the Botanical Department of the University of 
Michigan. 
171 
