43 BOTANICAL GAZETTE [JULY 
then the roots and glass tubes were sealed in with a vaseline- 
paraffin mixture by the Briccs and SHantz method. The total 
volume of the interstices (allowing for a definite water content) was 
previously determined, and upon the basis of this volume, known 
concentrations of gas could be secured. The duration of experi- 
ments was 5-21 days. Gases were changed every three days by 
drawing pure air through the jars for 10-15 minutes by means of 
an aspirator, and new gas added. Parallel experiments with 
ethylene were also run in many cases. 
2. Qualitative tests 
In this series of experiments it was desired to subject a number 
of plants to illuminating gas under conditions met with in the field 
where leaking gas mains are involved. Potted woody plants, 
including 36 individuals of 11 species, were used. Illuminating 
gas was allowed to pass slowly into the soil around the roots. 
Meanwhile symptoms of injury were noted. When the plant had 
died, or become seriously injured, or after a certain time had elapsed, 
the roots were washed clear of soil, and careful examinations made. 
The rate of gas flow was often less than one-eighth liter per hour. 
Results and discussion 
The results will be presented in the order in which the methods 
were described. 
A. EFFECT OF ILLUMINATING GAS ON SEEDS PLANTED IN SOIL 
PREVIOUSLY TREATED WITH GAS AND THEN AERATED 
In all cases, at the time of the planting of the seeds, the treated 
soil gave an exceedingly strong odor of illuminating gas. Of the 
41 species planted, 5 failed to germinate, but the failure was in 
both the controlled and the treated soils. Throughout the 25-60 
day period, the aerial portions of the seedlings were watched for 
signs of injury. However, it was found that the plants in all the 
treated soils gave no superficial evidence of injury. All seemed 
perfectly normal. At the end of the period the plants were taken 
up, their roots washed free of soil, and examinations made. Only 
two species gave any evidence of injury; these were cotton and 
lupine. In them the root systems were: perhaps somewhat less 
developed in the treated soils, and in the cotton there appeared to 
