G. GENERAL NATURAL HISTORY AND ZOOLOGY. 335 



cause of the phosphorescence of dead fish and dead animal 

 matter, but it is secreted by certain luminous worms (the Sco- 

 lopendra, etc.), and probably by all animals which shine in 

 the dark, and frequently by certain living plants (Aparicus, 

 Euphorbia, etc.). It is also developed by the decomposition 

 of vegetable matters, under certain conditions (fermentation 

 of potatoes, etc.). 



At the ordinary temperature noctilucine is an almost liquid, 

 nitrocrenized matter. It mixes with water, but does not dis- 

 solve in it, and appears to have a density little less than this 

 liquid. It is white, and, whether extracted from a living or 

 dead animal, is luminous, and possesses an odor resembling 

 that of caprylic acid. It is insoluble in alcohol and ether, and 

 is dissolved and easily decomposed by the mineral acids and 

 alkalies. When fermented in contact with water, it disen- 

 gages an odor of cheese. When fresh, it is strongly phosjmo- 

 rescent, the production of light being due to its oxidation in 

 contact with moist air. Indeed, it will shine as well in wa- 

 ter as in air. It is a little more brilliant in oxygen gas ; and 

 it has been observed that it is always most lustrous when the 

 wind blows from the southwest that is to say, when there is 

 most ozone in the air. As soon as the oxidation of all the 

 matter is accomplished the production of light ceases. If the 

 slightest quantity of air adheres to it, it shines for some mo- 

 ments in moist carbonic acid. 



In phosphorescent animals noctilucine is supplied from a 

 special organ as the bile is secreted by the liver and ap- 

 pears to be employed to produce light almost as soon as it is 

 formed. It is also produced in certain conditions of temper- 

 ature and moisture by dead animal matter of various kinds; 

 but, whatever its source, it always gives the same kind of light 

 that is to say, one that is almost monochromatic, giving a 

 spectrum principally visible between the lines E and F, and 

 possessing the same uniform chemical properties, as far as has 

 been observed. It is secreted in a state of considerable puri- 

 ty by the Scolopendra electrica, and by causing several of 

 these myriapods to run about on a large capsule of glass, 

 enough can be obtained to allow an examination of its prin- 

 cipal properties. From Lampyrus and the phosphorescence of 

 dead fish it can always be obtained in a state of less purity. 



The secretion of this substance by the luminous animals 



