360 BOTANICAL GAZETTE [MAY 
1. Check; epicotyls 6-11.5 cm. tall, vertical and slim. 
a) Potassium ferrocyanide-derived CO 
. 50CC.; epicotyls 4-6.5 cm. long, with declination of 20°-45°; 
seahius but larger diameter than checks. 
3- 100 cc.; epicotyls 3-5 cm. long; swelling 1-2 cm. long, with declination 
of 70°90". 
&. 200, Ct.; epicotyis 2.5-4.5 cm. long; swelling 1-1.5 cm. long, with 
declination 80°—90 
5. IOocc. Rater in bromine; epicotyls 3-5.5 cm. long; swelling 1-2.5 
cm. iad declination mostly 30°-60°. 
oo cc. washed in — epicotyls 2.5-4 cm. long; swelling 1-2 cm. 
long; Scitation 60°-9 
b) Oxalic acid-derived CO 
. 50CCc.; epicotyls 4-7.5 cm. tall; no swelling, but diameter larger than 
checks; fetta tion 25°-35 : 
8. 100 cc.; epicotyls 3-5. 5 cm. long; swelling 1-2. 5 cm. long; declination 
60°—90°. 
g. 200 cc.; epicotyls 3-5 cm. long; swollen zone 1-1.5, with declination 
75°—90°. 
c) Sodium formate-derived CO 
Io. 50cCc.; epicotyls 5-7 cm. long; no swelling, but declination 15°-40°. 
II. IOOCC.; ery 4.5-5.5 cm. long, with swelling 1.5-2.5 cm. long, 
and declination 60°—90 
12. 200 CC.; ‘steels 3-5 cm. long; swollen zone 1-2 cm., with declination 
70°90". 
A series of photographs will show the response to CO (oxalic 
acid-derived) of various concentrations (fig. 4). It is evident that 
the responses obtained in this experiment are due to the CO con- 
tained in the gases and not to impurities. When the data and 
figures on CO are compared with those on smoke from paper 
cigarettes, it is seen that the smoke is about 10 times as toxic 
as pure CO; 10 cc. of the smoke give responses similar to 100 cc. 
of CO, and 20 cc. of the smoke similar to 200 of CO. Since the 
smoke is approximately 15 per cent CO, it contains only about ;'y 
enough CO to determine its toxicity. This helps to substantiate 
the conclusion that the heavy hydrocarbons determine the toxic 
limit of paper and tobacco smoke, so far as the plant organ studied. 
is concerned. 
