54 NAXU1UL HISTORY SGCIGXK OK DUBLIN. 



fleeted the needle of the multiplier from 3° to 7°, the head at the Same 

 time appearing to be positive. Non- luminous insects, even when they 

 moved on the cushions, usually afforded, with a multiplier of 16,000 

 turns, no indication whatever of a current, or, at most, did not deflect 

 the needle more than 1° or 2°. * From the foregoing experiments, 

 coupled with the anatomical facts, Kolliker concludes that the luminous 

 organs in the genus Lampyris are a nervous apparatus, whose nearest 

 analogues might be sought in the electrical organs, and that the lumi- 

 nous matter, which is of an albuminous nature, and is abundantly 

 supplied with oxygen by its numerous tracheae, undergoes during 

 life a decomposition, one of the ultimate results of which is urate 

 of ammonia, which is found to be contained largely in the white cells. 

 The luminosity of Lampyris is quite hereditary, for the eggs and 

 larvae are phosphorescent, as well as the perfect insect. If the lumi- 

 nous matter be extracted from its receptacle, the part heals and becomes 

 filled again with a fresh supply. M. Moren,f Professor of Botany in 

 the University of Liege found that when the spiracle next to the lu- 

 minous material in L. Noctiluca is closed, the light is immediately ex- 

 tinguished, and reappears when it is opened, as thetrachean ramifications 

 which surround the luminous matter issue from a spiracle situated 

 immediately at the side of the luminous mass. 



The light of the phosphorescent Elateridse of America, which is 

 emitted from three principal points, has been examined with the spec- 

 troscope, but as yet without increasing our knowledge of the pheno- 

 menon. The spectrum produced by the firefly of New Hampshire was 

 perfectly continuous, without traces of lighter or darker lines, extending 

 from a little above Frauenhofer's line C in the scarlet to about F in 

 the blue, gradually fading at the extremities. The spectrum of their 

 light is continuous, without any black rays ; it differs from the spectrum 

 of the solar light merely by a greater intensity of the yellow colour. It 

 is considered to be probably produced, as in Lampyris, by the slow 

 combustion of a substance secreted by the animal. The splendour of 

 the light can be decreased or diminished, at the will of the beetle, by 

 means of membranes which it interposes like screens in front of the 

 phosphorescent lamps which it has on, what is popularly called, its 

 forehead. Professor Van der HoovenJ of Leyden got possession of an 

 Elater noctilucus, which had been imported in a cargo of logwood, 

 after it had lived some weeks in other hands ; he kept it alive for a 

 fortnight. The phosphorescent spots were, in the dark, first blue, then 

 emerald green, then incandescent. Large printing could be read by 

 the light, but it was necessary to carry the insect along the lines to 

 read continuouslj T . In their native country, on a dark night, their 

 light cau be seen at about 200 paces distant. In oxygen gas the lumi- 



* " Quart. Jour, of Microscop. Science," 1858, vol. vi., p. 1( 

 f Kirby & Spence, " Entomology," 7tli ed., p. 512. 

 \ " Handbook of Zoology," vol. i., p. 526. 



