1908] CROCKER AND KNIGHT—CARNATIONS 271 
corked in a 20-liter carboy (containing air only) for 24 hours; ¢, a flower 
before being corked in a 20-liter carboy; and d, the same after being 
corked in 12 hours with o.5°¢ of illuminating gas. This shows that 
0.5°° of illuminating gas per 20,000 (1 part in 40,000) causes the com- 
plete closing of the flower in 12 hours or less. Higher concentra- 
tions caused a more rapid closing and a marked inrolling of the 
petals. With 0.5°¢ per 20,000 and less the inrolling is not conspicu- 
ous. Even 0.2°° per 20,000 causes considerable closing in 12 hours, 
though not as marked as o. Bors 
The effect of duration of exposure was also tested. No injury 
was done to a bud just ready to open upon one day’s exposure to 2°° 
FIG. 4.—a, a flower that has just opened; b, the same after being corked in a 20-liter 
flask of air for 24 hours; c, a flower that has just opened; d, the same after being 
exposed 12 hours to 1 part of illuminating gas in 40,000; ¢, result of treating a flower 
that Just opened for 12 hours with 1 part of ethylene in 2,000,000. 
of gas per 20,000 (four times killing concentration for three days’ 
©xposure), On a similar bud 5° for one day was considerably more 
'Njurious than o, 5°° for three days. The stigmas did not project, but 
the petals were markedly discolored. 
During the entire period of experimentation there was no very 
marked variation in the toxicity of the gas used.’ 
eff = determining the toxic limits we located a concentration that produced the 
a while one-half that concentration did not. It is clear that this permits consider- 
© Va iati : é 
