346 BOTANICAL GAZETTE [MAY 
brings together all the main conclusions of the work, and empha- 
sizes the bearing of the findings upon the growth of plants in dwel- 
lings, laboratories, etc. 
Seedlings (Vicia sativa, Pisum sativum, Cucurbita Pepo, Phaseolus 
vulgaris, and others) are very sensitive to tobacco smoke. In its 
presence Vicia sativa epicotyls show what we have termed the triple 
response, also they fail to develop anthocyanin, a feature RICHTER 
(38) has observed for many plants grown in laboratory air. MOLISCH 
states that one to three whiffs of cigar or cigarette smoke in a 
4.3-liter container caused the triple response. Smoke of paper, 
straw, and wood has effects similar to tobacco smoke, while fumes 
of nicotine have little influence on the seedlings. Carbon monoxide, 
pyridine, and hydrogen sulphide, in considerable dilution in the 
atmosphere, produce effects similar to smoke. MOLIScH quotes 
Pontac as showing that cigar and cigarette smoke bear consider- 
able quantities of carbon monoxide. On the basis of these data, 
Mottsc# concludes that carbon monoxide is probably the con- 
stituent determining the toxic limit of tobacco smoke for seedlings. 
Acquaintance with the work of Netjuspow (25), CrocKEeR and 
Kwnicut (6), and LEHMANN (18) should have led him to recognize 
the high toxicity of ethylene for epicotyls of seedlings and other 
plant organs, the rather low toxicity of carbon monoxide, and the 
universal presence of ethylene in tobacco smoke. This immediately 
suggests the probability of ethylene being the constituent determin- 
ing the toxicity for seedlings. Motiscn’s ‘whiff’? methods are 
poorly adapted for matching the amount of carbon monoxide in 
the applied smoke against the amount demanded to produce the 
response. 
Many microorganisms are likewise remarkably sensitive to 
tobacco smoke. A whiff of tobacco smoke blown across a culture 
of Pseudomonas lucifera “puts it out” in o. 5-1 minute. It readily 
recovers its power to phosphoresce when returned to sea water. 
Chromatium vinosum, Beggiatoa, Spirillum sp., Amoeba, Vorticella, 
Paramoecium, Didymium nigripes, and Gymnodimium fucorum are 
very sensitive to tobacco smoke, while Pinnularia and Phycomyces 
nitens are rather resistant. 
Adult vascular plants behave variously toward the impurity. 
