1908] 



CROCKER AND KNIGHT— CARNATIONS 



271 



corked in a 20-liter carboy (containing air only) for 24 hours; c, a flower 

 before being corked in a 20-liter carboy; and d, the same after being 

 corked in 12 hours with o.5 cc of illuminating gas. This shows that 

 o. 5 CC 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 o. 5 CC per 20,000 and less the inrolling is not conspicu- 

 ous. Even o. 2 CC per 20,000 causes considerable closing in 12 hours, 

 though not as marked as o.5 cc . 



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 CC 



'- * *. ' 



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; e, 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' 

 exposure). On a similar bud 5 CC for one day was considerably more 

 injurious 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. 1 



1 In determining the toxic limits we located a concentration that produced the 

 effect while one-half that concentration did not. It is clear that this permits consider- 

 able va-iation without detection. It is not possible to locate the toxic limits more 

 closely, due to the variation in the flowers. It is clear, however, that this gives a very 

 good idea of the magnitude of toxicity. 



