FOOT ON ANIMAL LUMINOSITY. 55 



nosity was not more splendid. Experiments to determine whether the 

 temperature rose with the phosphorescence were interrupted by the 

 death of the animal. On dissection, nothing peculiar was observed be- 

 neath the spots on the thorax, exceptlarge or smaller masses of the adipose 

 body connected by numerous tracheae. The two spots on the thorax, 

 through which the light issued, though destitute of the brown colouring 

 matter, and therefore translucent, were of the same thickness as the 

 neighbouring integument. Does this thickness, he asks, account for the 

 transmission of the green light, whilst that which proceeds occasionally 

 from parts of the inferior surface, where the membrane is thin, is 

 yellowish ? 



It is a remarkable fact how seldom a red light is emitted from lumi- 

 nous animals; green, blue, white, yellowish, and various shades of these 

 colours, are the ordinary tints of their phosphorescence. In the case of 

 a strange coleopterous larva of Brazil, lights of two colours are pro- 

 duced — red from the head, and green from the sides.* The light of 

 luminous animals has been observed to become red as they were about to 

 die.- Darwin remarks that in all the different kinds of glowworms, 

 shining elaters, and various marine animals which he has observed, the 

 light has been of a well-marked green colour. 



The wide distribution of a vital luminous property throughout the 

 animal kingdom may be gathered from the long list of animals which 

 have been ascertained to be possessed of it, and probably the catalogue 

 will be greatly enlarged in the progress of future investigation. 



The objects of this luminosity are probably various — to some ani- 

 mals it is protective and a means of defence. A carnivorous beetle has 

 been seen walking round a luminous scolopendron, apparently deterred 

 from attacking by the brightly-shining light. "When M. Quatrefages was 

 one night prosecuting his investigations on the phosphorescence of the 

 6ea at Boulogne, a dog came down to the edge of the water, and barked 

 at him in his boat. A can full of water thrown upon the sea in the di- 

 direction of the dog, caused such a blaze of light, that the animal ran 

 howling away, probably mistaking it for fire. Another object of the 

 light is sexual attraction: the apterous female of our English glowworm 

 beacons the male to her by it. Dr. Browne, in his " History of Jamaica" 

 (1789, p. 433), describes the mode in which the negroes hold a firefly, or 

 even a lighted stick, between their fingers, and wave it up and down, so 

 that it may be seen by others (fireflies), who, taking it for some of their 

 kind, fly directly towards it, and pitch upon the hand, unless they discover 

 the deceit before they come too near. In other animals the luminosity 

 appears to be an inherent quality, inalienable from their organism as 

 long as their vitality is preserved. 



The nature and the cause of the luminosity of living animals, of 

 physiological phosphorescence, cannot be yet precisely stated. To some 

 it is not satisfactory to assert that it is phosphorescence, or an evolu- 

 tion of light from a body which undergoes thereby no loss of substance, 



Trans. Ent. Soc," N. S., vol. iii., p. 5 (I'roc). 



