217 



The Effect of Tobacco Smoke and of Methyl Iodide Vapor 

 ON THE Growth of Certain Micro-Organisms. 



(Abstract. Published in full in Am. Jour. Bot. 5: 1918.) 



C. A. LuDWiG — Lawrence University, Appleton, Wis. 



The work here abstracted was carried out under the direction of 

 Prof. F. C. Newcombe at the University of Michigan and was supple- 

 mentary to a similar investigation in which illuminating^ gas and its 

 constituents were employed. 



The organisms used in the case of tobacco smoke included 14 species 

 of bacteria and 2 of fungi, and in that of methyl iodide vapor 13 species 

 of bacteria and 2 of fungi. The cultures were on glucose nutrient agar 

 slants. The culture chambers were tubulated glass bell jars set in 

 crystallizing dishes and sealed with paraffin. 



The methyl iodide was introduced into the chamber on a pledget of 

 cotton attached to the end of a glass rod fastened in a stopper. The 

 stopper, in turn, was used to close the tubulature in the bell jar. 



When smoke was used it was introduced by means of a tube through 

 a two-hole stopper in the tubulature. The suction was provided by an 

 aspirator connected with the interior of the bell jar by a tube through 

 the second hole in the stopper. The tobacco was burned in a cob pipe. 

 In some tests the smoke was used without being treated in any way; 

 in others it was passed through one or two wash bottles of water. 



The results indicated that tobacco smoke is toxic to the organisms 

 tested but not so extremely toxic as to some phanerogams. In view 

 of the large number of compounds in smoke it is hardly worth while to 

 venture an opinion as to what substances caused the results observed. 

 The wash smoke, however, showed less toxicity than the unwashed 

 smoke. This would suggest that something capable either of being- 

 condensed or of being dissolved in water has some part in causing the 

 results. 



The effect of methyl iodide vapor was to kill the cultures where 

 the concentration was great enough. Where the concentration was 

 less it resulted in an initial great retardation in the development of the 

 streaks followed later by a very vigorous growth. 



^ The influence of illuminating- gas and its constituents on certain bacteria and 

 fungi. Am. Jour. Bot. ^: 1918. 



