GRAIN CONSERVATION 135 



note that they can remain in this condition for a 

 very long time and yet recover when again supplied 

 with fresh air. Ten weevils were sealed up in 

 practically pure carbon dioxide (99*8 per cent) 

 at room temperature for four days (96 hours). They 

 were then removed to ordinary air and incubated 

 at 31 C. (88 F.), when 7 of them slowly revived 

 and were still alive at the end of 48 hours. 



At higher temperatures they cannot withstand 

 the influence of the pure carbon dioxide for so long ; 

 nevertheless, even when kept all the time at 31 C. 

 (88 F.), in one experiment all revived completely 

 after 26 hours' exposure and in another 9 out of 

 10 revived after 42 hours. 



If now, instead of using pure carbon dioxide, 

 we use carbon dioxide with a moderate admixture 

 of oxygen, we get a very different result, and one 

 which I think is of great interest and some novelty 

 from the physiological point of view. Under these 

 conditions the weevils again became completely 

 motionless in a very few minutes, but they cannot 

 remain so long under the influence of the gas without 

 losing the power of revival. Thus, at 31 C. (88 F.) 

 in a mixture of 78*58 per cent C0 2 and 21*41 per 

 cent 0, after only 21 hours there were no revivals. 

 At the close of the experiment there was still 20*61 

 per cent of oxygen present, which again suggests 

 that death was due to poisoning by carbon dioxide, 

 certainly not to deprivation of oxygen. 



