30 RAMBLES OF A NATURALIST. 



to produce light. Fishermen are well aware of the 

 fact that a substance exudes from the bodies of some 

 Molluscs which shines in the dark like decayed wood 

 or putrid fish, and in these animals the phenomenon 

 no doubt depends on a slow combustion. Neverthe- 

 less, an observation made by MM. Audouin and 

 Milne Edwards seems to throw some doubt on this 

 explanation ; for these naturalists saw the phospho- 

 rescent liquid of the Pholades flow in a stream along 

 the bottom of a vessel filled with spirit, and com- 

 bine into one mass, where it formed a luminous 

 stratum without losing any of its intensity. It is 

 evident, therefore, that phenomena of a very differ- 

 ent nature have been confounded under the common 



and even to different genera of the Coleoptera. Those which are 

 met -with in France, more particularly in the neighbourhood of 

 Paris, belong to two species of the genus Lampyris ; the commoner 

 of the two is the Lampyris spkndidula, the other is the L. hemiptera. 

 In these two species the female alone possesses the faculty of 

 producing light. Unprovided with wings, and unable to leave the 

 tufts of grass or the thick bushes which conceal her, she would fail to 

 be discovered by the male insect, if nature had not provided her 

 with a species of torch, which she can light or extinguish almost at 

 will. The luminous organ occupies the three last segments of the 

 abdomen, and is formed by a tissue of a somewhat fatty appearance, 

 in which we discover a large number of trachea?. This abundance 

 of vessels, destined to convey the air into the phosphorescent portion 

 of the body, leads to the supposition that the production of light may 

 here be due to a sort of slow combustion, analogous, for example, 

 to that of phosphorus. The experiments of Macaire, and more 

 recently still those of M. Matteucci, have placed the reality of this 

 explanation beyond doubt. The light of the Lampyris is ex- 

 tinguished in all gases unable to support combustion, while it is 

 rekindled in oxygen, and carbonic acid is evolved. Hence, in this 

 respect, these insects present the same chemical relations as burning 

 charcoal. 



