Effects of certain Agents on Insects. 201 



became concentrated, the bee became restless ; in two or three 

 minutes it fell down, and after a tremulous movement of its limbs 

 for a few seconds, it became motionless. Taken out after being 

 in five minutes, it exhibited, in a few seconds, marks of reviving, 

 its limbs moving in the same tremulous manner as that observed 

 previously to its becoming torpid. On the following day it was 

 alive and tolerably active at 55°, as if nowise injured by the auction, 

 on it, of the gas. 



Azote. — Put a fly (Hcteromyza buccata) into this gas, obtained 

 from common air by the removal of the oxygen by phosphorus, 

 after which removal it was allowed to stand twenty-four hours 

 over water. The fly, in coming in contact with the azote, imme- 

 diately fell from the side of the tube, and, except a slight motion of 

 one of its legs, it appeared to have been rendered instantly torpid. 

 Taken out after two hours, it revived in about ten minutes, its 

 activity nowise impaired. 



Common Air. — Put a fly of the same kind as the preceding into 

 a tube, with common air, confined by a little cotton wool, in a 

 room where all the indoor experiments were made, varying in 

 temperature between 52° and 60\ From the 5th February, when 

 it was introduced, till the 2Gth, it seemed little affected ; on the 

 28th it was found dead. 



Put a fly (Musca lanio) in a tube, with a small quantity of air, 

 a few times its own volume. This was on the 4th of January ; on 

 the 5th the fly was languid ; on the 16th it was motionless. About 

 two hours after being taken out it showed marks of vitality, and 

 was soon tolerably active. Hardly an appreciable quantity of 

 oxygen, by the test of phosphorus, was found in the residual air ; 

 most of it had been converted into carbonic acid. 



On the 19th January put three flies of the same kind as the last- 

 mentioned, pretty active at 45°, into a tube full of water, and in- 

 verted it in water; a little air adhered to their wings. Shortly 

 after they were found motionless, the temperature of the room 56°. 

 In about ten minutes after being taken out they revived, and, 

 when dry, they appeared to be as active as before. 



Oxygen. — Introduced a fly of the same kind into this gas, over 

 water obtained from the decomposition of chlorate of potash. 

 Though swimming with its feet and part of its body immersed in 

 the water, for twenty-four hours, its activity was nowise im- 

 paired : — a few hours later it was found under the water and 

 motionless ; on exposure to the air of the room it did not recover. 

 On the 27th January introduced another fly of the same kind into 



