34 BOTANICAL GAZETTE [JULY 
marked effects entered: (a) swelling back of the root tip, and 
(6) turning and coiling of root (fig. 1); (3) concentration 1:40; 
growth in length greatly retarded, also considerable swelling; 
coiling present, but the coils smaller and tighter. 
With ethylene—(1) Concentration 1:100,000 (that is, corre- 
sponding to ethylene of illuminating gas with (1) above); appar- 
ently no effect; normal growth ensued; (2) concentration 1: 10,000; 
responses similar to those shown in fig. 1 but somewhat more 
pronounced; (3) concentration 1:1000; little or no growth in 
length; strongly swollen, no coils. 
The parallel experiments with ethylene gave some evidence 
that the toxic effect recorded for the illuminating gas may be due 
to ethylene present in that gas because corresponding concentra- 
tions of illuminating gas and the 
ethylene-air mixture gave quite 
5} parallel results. 
‘J 2. With entire plants 
Material, radish, mustard, and 
tomato. The roots and hypo- 
—Outline of Vicia Faba 
ae ‘does the effects of illumi. COtyls gave responses as follows: 
nating gas on growth; A, control. Radish.—Exposure period 48 
hours. 
With illuminating gas—(1z) Concentration 1:500; bending of 
root evident (similar to those of fig. 1); no coiling; no swelling of 
hypocotyl or root; (2) concentration 1: 5000; coiling and bending 
of root evident; no enlargement of hypocotyl or root. 
Mustard.—Exposure period 48 hours. 
_ With illuminating gas——(1) Concentration 1:100; coiling and 
bending of root evident (similar to those of fig. 1); swelling of hypo- 
cotyl evident; no swelling of root; (2) concentration 1:11,000; 
bending of root slight; no other effect; (3) concentration 1: 20,000; 
bending of root slight; no other effect. » 
Tomato.—Exposure period 3 days. 
With illuminating gas—(1) Concentration 1:500; swelling 
between stem and root (fig: 2); growth considerably retarded; 
(2) concentration 1:10,000; swelling as above, but less marked; 
