LECT. VIII. MUTILATED INSECTS. 161 



Effects of mixed Oxygen and Carbonic Jlcid. In a mix- 

 ture of 1 part oxygen, and 9 carbonic acid, I found that 

 these insects did not continue glowing longer than two or 

 three hours ; and in twelve hours died. I proved that, the 

 glow-worm can neither shine nor live long in a mixture of 

 2 parts carbonic acid, and 1 part oxygen ; and that in this, 

 also, a portion of the oxygen disappeared after the insects 

 had been there for some time. 



Carbonic acid gas appears to act on them deleteriously. 

 Luminous segments, introduced into>the preceding mixture, 

 yielded the same results, in regard to the duration of light, 

 as entire insects ; but with this exception, that the oxygen 

 absorbed, and the carbonic acid emitted, were in much 

 smaller quantities, and only about a fourth of what we ob- 

 tain with entire animals. The volume of gas which dis- 

 appeared during the experiment, is owing to the small 

 quantity of water introduced on the body of the insect, and 

 which dissolves the carbonic acid formed. 



Mutilated Insects. The observation of this remarkable 

 fact, that glow-worms continue to live for several hours 

 after being deprived of their luminous segments, induced 

 me to make a curious experiment, the result of which 

 agrees with that already stated. 



I introduced twenty living and very brilliant glow-worms 

 into a bell-glass, inverted over mercury, and containing 

 6-6 cubic centim. of pure oxygen gas. I carefully re- 

 moved the luminous segments from twenty other living 

 and very phosphorescent glow-worms, and put the insects 

 thus mutilated into another bell-glass, also inverted over 

 mercury, and containing 5-6 cubic centim. of pure oxygen 

 gas. Lastly, the remaining twenty luminous segments of 

 the kst mentioned insects, were placed in a third graduated 

 bell-glass, with 9 cubic centim. of ogygen, in the same 

 manner as the preceding. In ten hours I examined the 

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