17$ APHIS. 



leaf of considerable length, taken from a stove 

 plant beset with Aphides of a dark lead-colour, 

 which were feeding on it in great numbers. On 

 immersion they did not quit the stalk, but imme- 

 diately their bodies assumed a kind of luminous 

 appearance from the minute bubbles of air which 

 issued from them. They were put under water at 

 a quarter past six in the evening, and taken out 

 at a quarter past ten the next morning, having 

 continued immersed sixteen hours. On placing 

 them in the sunshine some of them- almost im- 

 mediately shewed signs .of life, and three out of 

 four at least survived the immersion. One of the 

 survivors, a male, very soon became winged, and 

 another, a female, was delivered of a young one. 

 Many years before this experiment, with a view 

 to destroy the Aphides, which infested a plant in 

 my green-house, I immersed one evening the 

 whole plant, together with the pot in which it 

 grew, in a tub of water. In the morning I took 

 out the plant, expecting with certainty to find 

 every Aphis dead ; but to my great surprize they 

 soon appeared alive and well: and thus in addi- 

 tion to the other extraordinary phenomena attend- 

 ant on these insects, we find that they are capable 

 of resisting the effects of immersion in water for 

 a great length. When taken from the plant on 

 which they feed and kept under water, they do 

 not survive so long; their struggling in that case 

 perhaps exhausts them sooner. This part of the 

 subject might perhaps be pushed much farther: it 

 is sufficient for our purpose to have shewn that 



