S6 



HARDWICKE'S SCIENCE- GOSSIP. 



He was, probably, speaking of L. Italica. The 

 Homau naturalist, too, notices the appearance and 

 sudden disappearance of the light when the beetle 

 is on the wing (nunc pennarura hiatu refulgentes, 

 nunc vero compressu obuinbratse) : in wingless 

 females, at least, this light is subservient to the 

 will of the animal. In another portion of his work 

 (1. xviii. c. 66), he tells us that harvest-time is 

 always accompanied by the presence of these insects. 

 Dr. Holland thus quaintly translates the passage : 

 " Now the signe common to them both, testifying 

 as well the ripenesse of the one as the seednes of 

 the other, are the glo-birds, or glo-worms, Clcitidelae, 

 shining in the evening over the corn-fields : for so 

 the rustical paisants and country clownes call 

 certain flies or wormes glowing and glittering star- 

 like, and the Greekes name them Lampyrides ; 

 wherein we may see the wonderful! bountie and 

 incredible goodnesse of Nature in teaching us by 

 that sillie creature." 



It is perhaps fair to mention that Pliny does 7tot 

 attempt to lower the insects in the estimation of his 

 readei's. 



There have been many speculations concerning 

 the nature of the light ; some would call it an 

 electrical, and some a chemical phenomenon. "It 

 is probable," says Goldsmith, " that the little animal 

 is supplied with some electrical powers, so that by 

 rubbing the joints of its body against each other, 

 it thus supplies a stream of light." (" Animated 

 Nature," ed. 1782, viii. 141.) 



Goldsmith, maybe, developed this hypothesis 

 from the fact that when the yellow matter of the 

 light-producing organs is rubbed between the 

 fingers, luminous streaks become apparent. Hum- 

 boldt thought that the luminosity ia living animals 

 depended on " nervous irritation," as it was ex- 

 cited by galvanism ; for when he brought zinc and 

 silver in contact with the ganglion of the fore-foot 

 of an expiring Elater noctiluciis, strong phos- 

 phorescence was emitted. ("Views of Nature," 

 ed. Otte, p. 250.) Some physiologists do not 

 appear to be at all clear even as regards the portion 

 of the body whence the effulgence proceeds. For 

 instance. Dr. Carpenter, in one of his Manuals 

 (" Animal Physiology," § 399), declares the light 

 issues from the zmder surface of the three last 

 abdominal plates ; whereas in his " Zoology " 

 (§ G21) he states that it springs from the upper 

 part of the same rings. Milne-Edwards is of the 

 last opinion, whilst the Rev. J. G. Wood mentions 

 both surfaces. In all specimens I have examined, 

 the light appeared to be evolved from both, but 

 that which is visible on the superior surface may 

 be looked upon as a reflection or absorption of the 

 light from below, where the organs are situated ; 

 this is clear from the fact that after death the 

 lower part only remains of a dirty white colour. 



Most writers agree that in the female oil. nodihica 



it proceeds from the inferior superficies of the caudal, 

 penultimate, and antepenultimate segments, although 

 it does not shine equally from these. 



In Kirby and Spence's " Introduction to Ento- 

 mology " it is set forth that in the anal segment the 

 light remained the longest, and was the first to re- 

 shine. Two minute specks of light are seen on this 

 segment.^aud in the remaining two the organs have 

 been succinctly described as " two large yellowish- 

 white luminous plates." 



Dr. Carpenter, again, declares that the male " is 

 not luminous; "the French anatomists, Louis Figuier, 

 W. S. Dallas, and others, have the same notion. The 

 first says the male, " qui est pourvu d'elytres 

 noiratres et d'ailes, n'est pas phosphorique." 

 ("ElemensdeZoologie,"p. 469.) But this is not 

 a fact : in the male the illumination is given out from 

 the ultimate segment ; the specks, however, are 

 smaller, and the phosphorescence differs in being of 

 a " greyish transparent hue." 



Rye says it is " sometimes " luminous, and the 

 Rev. S. Haughton informs us that it ceases " after 

 pairing, whereas the females are most luminous 

 while engaged in laying eggs." ("Three Kingdoms 

 of Nature," p. 321.) The larvae, pupae, and eggs are 

 also faintly lurid. With regard to the anatomical 

 structure of the organs. Professor Rymer Jones's 

 explanation is that these particular organs in most 

 insects agree inconsisting"of an investing membrane 

 enclosing a parenchyma composed of tracheae and 

 nerves, surrounding groups of cells so densely filled 

 with white, spherical, minute granules, having an 

 oily aspect when viewed by transmitted light, that 

 no other constituent canbe seen in them." (" Animal 

 Kingdom," third edition, p. 363.) Hence " KoUiter 

 concludes that the " luminous organs are a nervous 

 apparatus, whose nearest analogues are to be sought 

 for in the electrical organs of certain fishes." Others 

 describe the granular matter as being of a yellowish 

 colour. Professor Marshall further informs us that 

 the " sacs are closed by horny lids, having peculiar 

 flat surfaces suited to the diffusion of the light." 

 (" Outlines of Physiology," vol. ii. p. 525.) 



Most savans agree in supposing it to have a 

 chemical origin, being in fact an organic secretion, 

 which probably enters into chemical combination 

 with the oxygen of the atmosphere ; the effects of 

 which are a slow combustion. Dr. Packard quotes 

 Siebold, who thinks that the remission of the phos- 

 phorescence in fire-flies can be explained by this 

 theory, "and which coincides, not with the move- 

 ments of the heart, but with those of inspiration 

 and expiration," (" Guide to the Study of Insects," 

 second edition, p. 421.) The substance, whatever 

 it is, does not appear to contain phosphorus in any 

 appreciable quantity, and the product of its com- 

 bustion has been found to be carbonic anhydride. 



A glow-worm has been found still to retain its 

 luminosity when in vacuo, and whilst under water. 



