Insects. 4505 



for future use. On the other hand, the cyanide of potassium is reten- 

 tive of its properties, inexpensive, and may be kept any length 

 of time in stoppered bottles, — recommendations which will be appre- 

 ciated by the foreign collector. 



Little or no fluttering is observed during subjection to the vapour, 

 and the insect may remain with advantage for some time under 

 its action, as the muscles thus become supple and more manageable 

 for setting. 



A small phial for the pocket, furnished as above, will prove a great 

 help to those studying the Micro-Lepidoptera, as by its means speci- 

 mens may be obtained microscopically perfect. 



The Hymenoptera and Diptera are peculiarly sensitive to this 

 subtle poison. They generally begin to clean and plume their an- 

 tennae (perhaps an argument in favour of those who consider that the 

 olfactory nerves are placed in those organs), intoxication then seizes 

 the insects, they turn on their backs, and lastly a violent spasm affects 

 the muscles of the wings, which vibrate very strongly immediately 

 before death. 



During the last summer the instrument has been in pretty constant 

 use, and with the best results. I have met with but one failure in its 

 operation, which exception is perhaps sufficiently interesting to 

 notice. 



The fecundated female of the Burnet moth {Anthrocera Filipen- 

 clulae) resists the poison in a remarkable manner. A specimen was 

 placed in the apparatus in company with the black spectre-moth 

 (Mormo maura). The last large insect was dead in rather less than 

 two minutes, but the former was found to be comparatively lively 

 after the expiration of fourteen hours. It is worthy of remark 

 that during this exposure to the cyanide, oviposition did not take 

 place, but commenced immediately after liberation, exhibiting 

 perhaps a knowledge, on the part of the insect, that such an atmos- 

 phere would not conduce to the comfort of the larvae when excluded 

 from the eggs. Tenacity of life has been repeatedly remarked 

 by others under similar conditions. Many insects will deposit their 

 eggs long after the death, and even stiffening of both head and thorax. 

 These are, doubtless, wise and providential arrangements for ensuring 

 the perpetuation of species. It is, however, to be observed, that 

 the poison is inert, though in a less marked degree, on the male 

 Burnet moth. 



An exceptional case to the action of hydrocyanic acid has been 

 lately mentioned, relating to the frog, which, it is said, may be made 



