135 



the light of the glow-worm is extinguished in hydrogen 

 and carbonic acid gas. Sir H. Davy, on the other 

 hand, found that the light was not sensibly diminished 

 in hydrogen, and we have not only found the same 

 thing, but that the animal itself does not seem to suffer 

 materially in this gas ; and though it expires in carbonic 

 acid gas, the light suffers no eclipse by the fate of the 

 insect. Dr. John Davy found, at Kandy, on the 30th of 

 June, while the air was 73, that the temperature of 

 a large species of glow-worm was 74 Fahrenheit ; and 

 we have seen the thermometer affected by nearly a 

 degree from suffering the glow-worm to crawl over its 

 bulb. * 



On the night of the 10th of June, 1822, on return- 

 ing from Llanymennech to Oswestry, in Shropshire, 

 we picked up two glow-worms from the grass on the 

 roadside. The brilliancy was intensely beautiful 

 the penultimate and antepenultimate rings of the under 

 side of the abdomen were the portions illuminated, to- 

 gether with two luminous points on the anal segment] 

 The night was dry, and much lightning prevailed: we 

 repeatedly held the insects exposed and attached to the 

 spikes of grass to the repeated flashes of lightning which 

 played on them, but this seemed by no means to dis- 

 concert them ; for their luminous paraphernalia re- 

 mained still unveiled. One placed on the watch-glass 

 gave sufficient light to ascertain the hour : we arrived at 

 half-past 10 P. M., and introducing them into a room 

 with a candle, the light gradually diminished in inten- 

 sity, and became ultimately extinct, attenuating from 

 the edges of the bands or discs, and disappearing in 

 patches toward the centre. The thermometer stood at 



* Dr. Todd transmitted to the Royal Society a paper on the 

 glow-worm, subsequent to our communication on the subject to 

 Linnean Society. It appears to contain no novelty. 



