198 



ANIMAL LUMINOUSNESS. 



Fulgora pyrrhorliyncus 



candelaria 

 Pi/rulis minor 

 Achcta grylhttalpa ? 



MVRIAPODA 



Scolopendra dectrica 

 phosphorea 

 morsitans 



Julus ? 



ANNELIDA 



Nereis phosphoruns 

 noctiluca 

 cirrigera 

 mucronata 

 Planariu retusa 



EclIINODERMATA 



Asterias 



Ophiura telactes 



phosphorea 



ACA LEPHJE. Almost all the species of Medusa, 

 Beroe, Physalia, Rhizophora, Stephanumia, 

 and Pliysopltora. 



ZonPHYTA 



Pennatula phosphorea 



grisea 



rubra 



argent ia 



INFUSORIA. Many species belonging to the 

 genera Cercaria, Folvox, Vibrio, Trichoda, 

 Lincophcea. 



With regard to fishes, the statements of 

 naturalists are so contradictory that we still 

 hesitate to admit any of them on the list of 

 truly luminous animals. The sharks, more fre- 

 quently than other fishes, are reported as lumi- 

 nous. The light given out by them is said to 

 proceed from their abdominal surface. When 

 large shoals of fishes are swimming rapidly, 

 flashes of light, broad and deep, are sometimes 

 seen about them and are supposed to be 

 emitted by the fishes themselves. These appear 

 occasionally at very great depths. They have 

 been traced in the British seas to shoals of 

 herrings and the coal-fish ; and Dr. M'Culloch 

 enumerates also the pollack, the pilchard, the 

 sardine, the whiting, the mackarel, and the gar, 

 as being sometimes accompanied by these 



lights.* 



. The common earth-worm is not included in 

 the above list, although several observers have 

 reported it as luminous, because the fact of its 

 being so is not sufficiently determined. It is 

 said to give out light only during the period of 

 propagation. 



Some voyagers, as Peron, have stated that they 

 have seen sertulariee, gorgonite, alcyonia, and 

 sponges give out light immediately after being 

 di edited from the bottom of the sea ; but we sus- 

 pect that in most of these instances the light 

 proceeded not from the zoophytes, but from 

 some light-givingannelidsparasiticalupon them. 

 This is frequently met with in the British seas. 

 II. Characters andpropertiesof animal light. 

 It is only in its most obvious qualities that 

 animal light has hitherto been the object of 

 scientific research. In colour and intensity it 

 varies very much at different times in the same 

 animal, and still more in different animals. 



* Edin. Encycl. art. Phosphorescence. 



With regard to colour the following varieties 

 occur. In pholas dactylns the light is bluish- 

 white ; in lampyris noctiluca it is greenish with 

 a shade of blue ; in I. italica, bright blue; in 

 Elater noctilucus, brilliant green, with spots of 

 " the most beautiful golden blue ;" in Fulgora 

 pyrrhorynchus, deep purple and scarlet; in 

 marine animals generally it is white with various 

 shades of blue. Doubtless these differences 

 depend chiefly upon the various colours of the 

 integuments through which the light is seen. 



In lampyris italica, there are alternate emis- 

 sions and extinctions of the light, which take 

 place with some degree of regularity and seem 

 to be synchronous with the pulses of the cir- 

 culating current, visible in the wing-cases of 

 this beetle.* 



The fire-fly (Elater) shews two kinds of 

 light; one constant, like that of the glow-worm, 

 but more feeble ; the other a vivid white light 

 suddenly intermitted. Its illuminating power 

 seems to be greater than that possessed by any 

 other animal ; the light emitted from its two 

 thoracic tubercles is so great that the smallest 

 print may be read with it ; and in the West 

 Indies, (particularly in St. Domingo, where 

 they are abundant,) the natives use them in- 

 stead of candles in their houses. They also tie 

 them to their feet and heads in travelling at 

 night to give light to their path through the 

 forest. The intermitting of the light in this 

 insect is such as to give an observer the idea of 

 a membranous veil being suddenly drawn over 

 the source of light, and then as suddenly with- 

 drawn. 



In a species of cancer seen by Smith in 

 the Gulf of Guinea, the light (which seemed to 

 be emitted by the brain) was of a deep blue 

 colour when the animal was at rest ; but when 

 it moved, bright coruscations of silvery light 

 were darted from it in all directions. The light 

 of some centipedes inhabiting the islands of 

 the Pacific is of a beautiful emerald-green 

 colour. It is connected with a mucous matter 

 covering the animal, which may be rubbed off 

 by the fingers, and communicates to them a 

 smell not unlike that of muriatic acid. 



Sometimes the light proceeding from the sea 

 is so white and dull as to give the effect of a 

 sea of milk. This is frequently seen in the 

 Gulf of Guinea, and seems to be caused some- 

 times by the presence of numerous Sulpte- and 

 Sci/llari, at other times by the admixture of the 

 debris of fishes and other marine animals re- 

 cently dead. 



An extraordinary series of phenomena con- 

 nected with a particular display of the lumi- 

 nousness of the sea, is reported by Mr. Hen- 

 derson as having occurred in the Atlantic, 

 (lat. 2 long. 21 20' W.) on the 5th March, 

 1821. About 9 p.m. the sea appeared unusu- 

 ally luminous. Every person who kept his eye 

 fixed upon it for but a short time was immedi- 

 ately affected with giddiness, headache, pain in 

 the 'eyeballs, and slight sickness. Although 

 these symptoms varied in intensity amongst the 



* A species of lampyris lately found in New Hol- 

 land is said also to shine in rhythmical pulses. Isis, 

 vol. ii. p. 245. 



