1(U JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 2 



air under an atmospheric hiunidity of about 65 to 70 per cent of sat- 

 ui'ation. 



In a comparison of lots of seed treated alike before and during the 

 oas exposure, but in which one series was placed in water for soakinp- 

 preparatory to germination immediately after being removed from the 

 gas and weighed, while a parallel series was allowed to air for twenty- 

 four hours before they were germinated, there appeared to be a greater 

 injury among the seeds which were not allowed to evaporate their ab- 

 sorljed gas before being soaked in water. In the check lots the aver- 

 age percentage of germination was 91 ; in the treated seed which was 

 aired it was 73, while in that not allowed to air it was but 65 per cent. 

 Tn lioth series the seed treated from four to six days germinated prac- 

 tically as well as did that ti'eated from one to three days. The in- 

 creased length of treatment did not result in a proportionate injury to 

 the germinative power of the seeds. In no ease was the injury as great 

 as that reported by Ilieks and Dabney for a forty-eight hour treat- 

 ment. It is evident that the proportion of water in the seed at th',' time 

 of treatment has much to do with the possil)ility of gas injury. We 

 have not concluded our investigations along this line. 



The second part of our work is concerned witli the effects of the gas 

 upon insects either as adults outside of the seed or as immature stages 

 within the seeds. In this work a saturated atmosphere was used in 

 bell-jars, as with the germination experiments. The minimum time 

 for each series of experiments was taken as the time at which all in- 

 dividuals in a lot appeared to have succumbed to the effects of the gas 

 and remained quiet. From this time on each lot was given an added 

 exposure of five minutes. After the treatment the insects were left un- 

 disturbed to air for about eighteen hours and were then carefully ex- 

 amined. All specimens, whether apparently dead or evidently alive, 

 were preserved for further continued observation and in numerous 

 cases it was thus found that insects recovered activity after from one 

 to two days, during which they had showed no sign of life. 



In the experiments with adults of Bruchus chinensis more than fifty 

 per cent was killed in twenty minutes in the gas and about ninety per 

 cent in thirty-two minutes. Among over two hundred adults treated 

 for forty-five minutes only two ever moved after being removed from 

 the gas, and these did not recover sufficiently to feed. With the im- 

 mature stages, under similar conditions of treatment, practically all 

 stages were killed in a thirty-minute treatment. The effects upon the 

 eggs of this species and upon the germination of cow-peas have not yet 

 been determined. This species is much more easily killed than either 

 of the other two which have been studied particularly. 



