132 GENERAL NOTES 



suicide has notliiug to reeomineud it, iiuless it >?Iiould 

 happen that self destruction is the habit only of weak- 

 lings. If it can be shewn that scorpions deliberately 

 sting themselves with fatal consequences under any cir- 

 cumstances to which they may be subjected in nature, 

 the case will witness strongly against natural selection 

 as a prime factor in evolution ; however, according to 

 modern views, the importance of Natural Selection has 

 been somewiiat overrated, and thus theoretically scorpion 

 suicide comes within the range of possibility. 



John HEwrrr. 

 Albany ^Juseum, 

 Grahamstown. 



The Stimulating Influence of certain Gases 

 ON Insect Pupae. 



During the years of 1914-15 when the writer was en- 

 gaged upon some fumigation experiments against the 

 Angoumois grain moth {Hitotroga cerealeUa Zell.), a 

 peculiar effect was noticed. Hydrocyanic acid ga*^ was 

 used, but even at strong strengths it did not readily 

 penetrate the grain, consequently the pupae of the insect 

 were not killed. However, a small amount of the gas did 

 ])enetrale the grain but instead of injuring the ])upae 

 it a]>}/ai-ently exerted a stimulating influence upon them, 

 with the result that in most cases moths issued from 

 pupae in grain that had been subjected to fumigation 

 sormer than from those in gi-ain tliat liad not been exposed 

 to the gas. 



In 1018, one fumigation test with sulphur dioxid': was 

 made. The strength cf gas used did not prove sufficient 

 to kill the pupae. It was noticed in this case also that 

 moths issued from llie grain that had been fumigated, 

 sooner than from an untreated check lot. Recent experi- 

 ments indicate that weak strengtlis of carljon bisu-pliide 

 will jn-obably liavc the same effect, but this is not 

 altogetlier cerlaiiL 



