200 Dr. John Davy on the 



gas. They became motionless in a few seconds ; left in about an 

 hour, the former did not revive immediately on being taken out, 

 nor even when placed on the warm hand and breathed upon ; yet 

 in half an hour it was nearly as active as before. The other fly, 

 similarly treated when taken out, revived in less than a minute on 

 the warm hand. Again immersed in the gas, and now left there 

 about twenty hours, both were found to be dead when taken out. 



On the 29th December, repeated the experiments on two flies 

 similar to the preceding, with a like immediate result, they be- 

 coming motionless in two or three seconds, Taken out after two. 

 hours, they did not revive immediately, even when placed on the 

 warm hand and breathed upon ; in ten minutes they had revived, 

 and were much in the same state as to activity as before immersion : 

 the one alert (the Heteromyzd), the other sluggish. Thrown again 

 into the gas, they instantly became motionless, — not the slightest 

 movement, even of the legs, could be perceived ; had the air in the 

 tube been common air, they would have been excited by the fall ; 

 taken out instantly they presently revived. Returned into the gas 

 on the following day, and taken out after three hours, both were 

 found motionless ; the Heteromyza, after six hours, was found 

 active ; the other fly then was motionless, not moving even when 

 touched ; nine hours later it was revived, and active. 



On the 9th March placed two honey bees, rather languid at 55°, 

 in the tube, in which carbonic acid gas was in the act of being 

 disengaged ; common air was mixed with the gas. They at first 

 became excited and active, used their wings, as if trying to escape; 

 gradually, and pretty rapidly, their activity diminished; and in less 

 than a minute they both dropped down on the diaphragm motion- 

 less. Taken out, after remaining in about a quarter of an hour, 

 they remained motionless about an hour and a quarter; now 

 breathed on, they began to move, and shortly, at a temperature 

 of 65°, to which they were transferred from one of 51°, they be- 

 came active. 



HydrogenGas. — On the 30th December immersed the same flies, 

 which had revived after exposure to carbonic acid gas on the pre- 

 ceding day, to hydrogen whilst in the act of being generated by 

 means of zinc and dilute muriatic acid. They did not become 

 instantly motionless, but they were so in less than a minute. Taken 

 out after being two hours in the gas, the Heteromyza revived in 

 about a quarter of an hour ; the other remained motionless about 

 three hours, then, when touched, it moved freely. 



On the 10th March made a similar experiment on a honey bee. 

 As the hydrogen, from the expulsion of common air from the tube, 



