SCIENCE-GOSSIP. 



167 



CHAPTERS FOR YOUNG NATURALISTS. 



{Continued from page 142.) 



Living Lamps. 



By Francis M. Duncan. 



"THE beautiful and mystic light which is to be 

 seen playing over the surface of the sea and 

 illuminating the waves as they break upon the 

 shore, is known to us by the name of phosphor- 

 escence, and is produced by myriads of tiny 

 creatures called Noctilucae — literally, night-lights. 

 Sd minute are these creatures that a single speci- 

 men is but little more than visible to the naked 

 If we examine one of these specks of jelly, 

 we shall find it almost a complete globe in form, 

 provided with a whip-like process, or member, 

 which is used as a means of locomotion. If 

 watched, the light of Noctiluca miliaris will be seen 

 to appear and disappear with considerable regu- 

 larity, and should the animal be touched with a 

 needle point, the light is quickly visible; just 

 before death it becomes continuously luminous, 

 tie phosphorescence disappearing immediately 

 after dissolution. Various interesting and curious 

 experiments have been made with these little 

 creatures, a goblet filled with them being used on 

 one occasion as a lamp wherewith to read. A 

 tube, fifteen millimetres in diameter, containing a 

 bed of Noctilucae at the surface, twenty milli- 

 metres thick, emitted light sufficient to see the face 

 of a watch and read the figures on the dial, and, 

 when agitated, the little creatures were found to 

 give sufficient light for the face of the watch to be 

 clearly seen at the distance of a foot. 



With this wonderful light there is no perceptible 

 heat ; the most delicate thermometers are not 

 affected by it, and that it is not produced by 

 combustion may be assumed from the fact that 

 oxygen gas, when introduced, has not been found 

 to restore the light after it has disappeared at the 

 death of the animal. 



Nearly all the jelly-fish or medusae become 

 js at night, and are very interesting to 

 watch as they move about in all directions, 

 illuminating the depths of the sea with their 

 mysterious phosphorescence ; some emitting a pale 

 greenish or steel-blue light, others crowned with 

 a golden radiance. Some idea of the wonderful 

 light emitted by the jelly-fish may be gathered • 



.•: description of Ittunioftil Itidyii.t highly 

 phosphorescent form, by • I'rofessor Alexander 

 Agassi/, fie states that when passing through 

 sboals of these medusae, the whole water became 

 •o luminous that "an oar dipped in the water up 

 to the handle could be seen plain!} nights 



by the light so produced." 



Let us now turn our attention to the floor of the 

 sea, for here also living lamps abound, and could 

 we but traverse the deep valleys and hills that are 

 hidden beneath the surface, marvellous and awe- 

 inspiring would be the sights that would meet our 

 eyes : forests of luminous corals overhead, and at 

 our feet phosphorescent ferns, flowers, and weird 

 creeping things. The sea-anemones may well be 

 called the flowers of the sea valleys ; gorgeous in 

 colour and varied form, some of these attach 

 themselves to the shells of hermit-crabs, doubtless 

 acting as beacons to attract prey.' Many of these 

 sea-anemones emit a brilliant light, and continue 

 to do so even when brought to the surface by the 

 dredge. One of the most brilliant is Urticena 

 nodosa, which is generally found in ooze, its 

 tentacles appearing at the surface, gleaming like 

 the rays of a star. 



The sea-fans and plumes, known by the family 

 nameof Gorgonia, and the sea-pens, or Pennatulidae, 

 clothe the slopes and valleys of their aqueous 

 world, filling it with the radiance of their lilac 

 phosphorescence ; forests of corals of varied hue 

 uplift their graceful branches, amongst which fish 

 of many shapes and sizes disport, many of them 

 emitting a brilliant phosphorescent light of their 

 own. Such is a brief outline of the marvellous 

 living lamps to be found at sea, a moderate des- 

 cription of which would fill many portly volumes, 

 and yet leave countless treasures undescribed. 



Although the lamps of the sea are the most 

 beautiful and varied, alike in colour and brilliance, 

 still on land we find, both in the animal and 

 vegetable kingdom, many living lamps which burn 

 with vivid radiance. Probably the best known 

 land-lamps are the glowworms (Lantpyris noctiluca 

 and L. splendidula). Their light is due to phos- 

 phorescent particles concentrated in two or three 

 of the abdominal segments. Kolliker and Macaire, 

 1 he eminent anatomists, are agreed that the light- 

 producing granules are of an albuminous nature, 

 while Matteucci, by the aid of chemical analysis, 

 has assured himself that they do not contain 

 phosphorus. The female glowworm (L. noctiluca), 

 is wingless, resembling closely the larva state of 

 the speci'js . but Nature, as if anxious to compen- 

 sate her for the loss of aerial locomotion, has 

 endowed her with a more brilliant light than that 

 of the male. In many of the exotic species both 

 sexes are are win il is a glorious sight on 



a dark night in the tropics, to see hundred 1 



