72 WORK AT HOME AND IN THE FIELD 



able for the pocket to a glass stopper, for its elasticity prevents 

 it from losing its hold, and the liquid from saturating your pocket 

 and its surroundings ; but a glass stopper is certainly better for the 

 stock solution kept at home. 



Most of the above remarks apply equally well to benzole and to 

 chloroform, but the latter is so powerful a poison that a very little 

 is required for a day's work, and consequently a very small 

 bottle is more convenient. The dealers in naturalist's appliances 

 supply metal ' chloroform bottles ' with screw stoppers and a small 

 nozzle that will allow the liquid to run out only in drops. This is 

 a very good arrangement, since it enables you to avoid the * drop 

 too much ' which is not only unnecessary and therefore wasteful, 

 but saves you from experiencing the disappointment 

 of an empty bottle before your work is half done. 



Some entomologists recommend the solid carbonate 

 of ammonium instead of liquid ammonia, but this is 

 not so powerful. It must be remembered that we 

 have the butterflies to consider, as well as our own 

 convenience, in the selection of the poisons we use. 

 It is the opinion of many well-known entomologists 

 that ' insects cannot feel pain,' and that we are there- 

 fore at liberty to deal with them in any way we please. 

 Still it is as well to save all possible suffering, and be 

 FIG. 45. THE satisfied with no killing box that is not practically 

 CHLOROFORM instantaneous in its effects . 



.DOTTLE. 



Among other poisons used by entomologists I may 

 mention sulphur fumes and tobacco smoke. The former may be 

 obtained by burning a little sulphur or a sulphured lucifer match 

 under the perforations of a killing box of the pattern described, and 

 the latter well, every smoker knows that. I should at once con- 

 demn the former method, at least for field work, as troublesome 

 and inconvenient ; and as to the other, I have tried the effect of a 

 puff (and many puffs) of tobacco smoke on an imprisoned insect, 

 but was so dissatisfied with the result that I am not likely to do so 

 again. - 



"We have now considered a good many insecticides more or less 

 suitable to our purpose, but there still remains the unsolved problem 

 as to which is the best. Each one has its advantages. For 

 convenience nothing beats the cyanide bottle. It is very speedy in 

 its action, and the use of a bottle is a little preferable to a metal 

 box, for you can always satisfy yourself as to its efficiency without 



