November 23, 191 1] 



NATURE 



1 1 1 



Nature of Light Emitted by Fireflies. 

 The nature of the light emitted by fireflies (Malacoder- 

 lidae fam., genus Luciola) has hitherto been very httle 

 nvestigated. The idea that it is phosphorescent seems to 

 lave been generally accepted. On observmg the beautiful 

 'reen fluorescence of the light emitted by the msect when 

 t is put in a glass tube, we were struck by the close 

 esemblance of this light to that of the Crookes's tube. 

 :ould it be like that of the X-rays? 



An inquiry was instituted to see how it affects photo- 

 fraphic plates through different media. Various media 

 vere tried, and the results obtained by interposing wood, 

 lark brown leather, flesh, and black paper are described 

 )elow. It may be remarked here that the light emitted by 

 he insect is so fitful and faint that it is rather difficult to 

 ceep it steady, and it will be too much to expect this faint 

 ight to give more than shades of varying depth on the 

 jlates. It was observed that the capacity of the insect to 

 iffect the photographic plate depends on the length of the 

 exposure. When the insect was put on a naked plate for 

 1 few seconds, it did not affect the plate, but when it was 

 similarly held on the plate for one minute, its effect was 

 distinctly visible. After a series of experiments, therefore, 

 two hours' exposure in the case of paper and flesh, and 

 three hours' exposure in the case of leather and wood, were 

 considered sufficient. 



(i) An extra rapid photographic plate was placed in a 

 dark slide, and three insects were then placed on the slide 

 beneath a watch glass ; the whole plate was affected and 

 ittave dark grey print after an exposure of three hours. 

 Without the insect, the plate gave a black print on a 

 two minutes' exposure to lamp-light. 



(2) An extra rapid photographic plate was enclosed in 

 English tanned leather of a dark brown colour i mm. thick. 

 The three insects were placed on the leather, with the result 

 phat the plate gave a dark grey print after three hours' 

 5xposure ; a similar plate, similarly enclosed, when exposed 



lamp-light for two minutes gave a black print 



(3) The three insects were placed in a small tube open 

 It one end, which was enclosed in a piece of flesh (mutton) 

 [.5 mm. thick ; this was placed on a naked plate in a 

 >lark room. Where the light was not intercepted by the 

 jlass of the tube, the plate showed a white print after an 

 'xposure of two hours. A similar plate was covered with 



1 piece of flesh of similar thickness and exposed to lamp- 

 iijlit ; the resulting print was dark grey after two minutes' 

 ■xposure. 



(4) A similar plate was enclosed in black paper and the 

 n sects placed on it beneath a watch glass ; the resulting 

 irint was, after two hours' exposure, light grey; while a 

 )latc similarly covered exposed to lamp-light for two 

 ninutes was very slightly affected, and gave a very dark 

 rrpy print. The plate exposed to lamp-light without any 

 nedia for two minutes gave a light grey print. 



It was seen that the insect light approaches lamp-light 

 n the intensity of its effect on the photographic pjate, even 

 vhcn the different media opaque to light are interposed 

 ' tween the two. 



he light emitted by the insect cannot therefore be taken 



phosphorescent. It may be, perhaps, premature to con- 



iude that some of the rays emitted by the insect are 



^rays, but it may be safely asserted that these rays are, 



t least, similar to X-rays and ultra-violet light in so far 



s they render certain opaque media transparent and are 



^"rcepted by glass. We hope this short note may be the 



' ursor of elaborate experiments on the subject leading to 



le definite results. Puran Singh. 



Hehra Dun, November 2. S. Maulik. 



tion, and that the species cited as genotypes are the correct 

 types according to the International Rules of Zoological 

 Nomenclature : — 



Clonorchis Looss, 1907, February i, 147-152, type 

 sinensis. 



Dicrocoelium Dujardin, 1845a, 391, type lanceatum = 

 lanceolatum (.= ? dendriticum sub judice). 



Fasciola Linngeus, 1758a, 644, 648-649, type hepatica. 



Fasciolopsis Looss, 1899b, 557, 561, type buskii (seu 

 buski teste Blanchard). 



Gastrodiscus Leuckart in Cobbold, i877e, 233-239, type 

 sonsinoii (seu sonsinoi teste Blanchard). 



Heterophyes Cobbold, 1866a, 6, type aegypiiaca = 

 heterophyes. 



Metorchis Looss, 1899b, 564-566, type alhidus. 



Opisthorchis Blanchard, i895f, 217, type felineus. 



Paragonimus Braun, iSggg, 492, type westermanii (seu 

 westermanni teste Blanchard). 



Pseudamphistomum Luehe, 1908, 428-436, type trtiti- 

 catum. 



Watsonius Stiles and Goldberger, 1910, 212. type 

 watsoni. 



(3) The following commissioners have not voted : — 

 Jaegerskioeld (Gothenburg), Looss (Cairo), Luehe (Koenigs- 

 berg), Pintner (Vienna), and Shipley (Cambridge). 



(4) Notice is hereby given that the undersigned will wait 

 until July i, 1912, for any zoologist to raise any objection 

 to any portion of this report, and that on that date all 

 names to which valid objection is not raised will be for- 

 warded to the International Commission on Zoological 

 Nomenclature with the motion that these names be included 

 in the " Official List of Zoological Names " provided for 

 by the Graz Zoological Congress. 



(5) All correspondence on this subject should be addressed 

 to the undersigned. 



C. W. Stiles. 

 (Secretary International Commission 

 on Zoological Nomenclature.) 

 Hygienic Laboratory, Washington, D.C., 

 November 11. 



"rematode Generic Names Proposed for the " Official 

 List of Zoological Names." 



'i) The International Corrmission on Medical Zoology, 

 lointod by the Graz International Zoological Congress, 



^ made its first report on the names of Trematode genera 



1 asitic in man. 



(2) Four members, namely, Blanchard (Paris), Monticelli 

 Naples), Stiles (Washington), and Zschokke (Basel), 

 nanimously agree that the following eleven names arc, 



om the present point of view of systematic zoology and 

 omenclaturc, the correct names for the genera in ques- 



NO. 2195, VOL. 88] 



Dews in 1911, 



It may interest readers of Nature to know that between 

 July 31 and September 5 this year I collected a total 

 amount of dew equivalent to one-fifth of an inch of water, 

 whilst in 1909, between August 3 and September 12, about 

 one-tenth of an inch was collected. That is to say that this 

 vear the dews were twice as heavy as in 1909, or we may 

 state that during the above-mentioned period of this year 

 the deposit of dew in my instrument was equivalent to 

 20 tons of water per acre. Of course, most of this was 

 evaporated, but that amount of water could have been 

 collected with adequate means. 



This year has been disastrous to the so-called dew-ponds, 

 and I would remind readers of the view expressed in a 

 letter to Nature of May 14, 1908, that the ponds^ are 

 " simply water butts in which rain-water is stored." A 

 pond on the summit of St. Boniface Down, Ventnor, which 

 I visited on September i this year, was absolutely dry. 



I have been led to write this note because Mr. Martin, in 

 his interesting letter in last week's Nature, p. 77, savs 

 that " this year the absence of rain for so long brought 

 about a remarkable absence of dew." This was not my 

 experience, except on two or three clear nights when the 

 air seemed to be very dry. 



The details of my measurements and of my instrument 

 I hope to publish elsewhere. Sidney Skinner. 



South-Western Polytechnic Institute, Chelsea, S.W., 

 November 18. 



The Colours of Fishes. 

 Interest as to the sources of colours in birds and insects 

 has been revived by Prof. Michelson in The Philosophical 

 Magazine for April, and by Mr. Mallock at the Royal 

 Society. The inquiry will be assisted if fishes may also 

 be included. Nature reveals no more vivid form of shift- 

 ing tints than we see in the common mackerel, which is a 

 fish without scales. In August I was able to watch them 

 immediately a'ter the fish had been taken from the sea 1 



