23 M. de Quatrefages on the Phosphorescence of 



animals is owing to what they absorb from the rays of the sun, 

 which they throw out again in the dark. 



Spallanzani regards phosphorescence as a kind of combustion 

 sustained by tlie oxygen of the air. 



According to BrugnatelH, the light is taken in with the food, 

 and disengaged by particular organs. 



Macaire considers the phosphorescent matter as composed of 

 pliosphorus and albumen. The variations of intensity apparent 

 in the light arise more or less from the coagulation of the albu- 

 men, a coagulation whicli is increased or diminished at the will 

 of the animal, and permits a more or less rapid combustion. 



Tiedemann, Darwin, H. Davy, Heinrich, Treviranus, Bur- 

 meister, &c., believe in the secretion of a liquid containing phos- 

 phorus, and in the combustion owing to the air introduced by 

 respiration. 



Macartney and Todd regard phosphorescence as due to the 

 nervous fluid concentrated and modified by certain organs, so as 

 to appear under the form of light. 



The author next proposes his own theory founded on a sort of 

 fusion bctAveen the two preceding. With Macartney, he admits 

 that phosphorescence is due to an imponderable agent, and com- 

 pares it to the production of electricity by certain fishes. But 

 considering the well-known fact of the luminous traces that cer- 

 tain animals leave behind them, he supposes that phosphorus 

 or an analogous substance may very well enter into the compo- 

 sition of tlie organs which produce the light. 



It is plain that Dr. Coldstream, in common with all the authors 

 whom we have cited, believed that phosphorescence should be 

 attributed to but one cause. 



This error M. Becqucrel* has avoided. After having shown 

 that in the Lampyris and other insects phosphorescence is the re- 

 sult of a chemical action at the control of the animal, IM. Becquerel 

 relates the obsevvaticns of Ehreuberg, and admits with him that 

 in certain inferior animals the production of light is owing to 

 a disengagement of electricity. IMoreover, he recalls the ob- 

 servations of MM. Quoy and Gaimai'd, who had seen under the 

 equator, near the island of Rawak, small zoophytes, which while 

 swimming rapidly, drew after them luminous trains. Finally, 

 M. Becquerel, resting on this fact, and on his own observations 

 made in company with M. Breschet, at Venice, in the waters of 

 the Brcnta, allows that the phos])horescence of the sea may be 

 owing to an organic substance intimately combined or mingled 

 with tlie water, analogous to that which covers the herring and 

 other fish when they are phosphorescent. 



"^ Traitc de Physique comparee, dans ses rapports avec la Chimie et les 

 Sciences naturelles, t. ii., 1844. 



