332 PHOSPHORESCENCE OF DECAYING ANIMAL MATTER. 



appointed for the lovers' rendezvous," would not seem so incor- 

 rect as the ideas of poets on subjects of Natural History too 

 frequently are. Regarding the uses of the luminosity of the 

 lower marine tribes, it is more difficult to form a definite 

 idea ; since many of them are fixed to one spot during the 

 whole of life, and in many others the sexes do not require to 

 seek each other. 



402. It not unfrequently happens, that an evolution of 

 light takes place from the bodies of animals soon after their 

 death, but before their decomposition has advanced far. 

 This has been most frequently observed to proceed from the 

 bodies of Fishes, Mollusks, and other marine tribes ; but it 

 has been seen also to be evolved from the surface of land 

 animals, and even from the Human body. Indeed, some 

 well-authenticated cases have been put on record, in which a 

 considerable amount of light was given off from the faces of 

 living individuals, who were near their end. All animal 

 bodies contain a considerable quantity of phosphorus ( 166) ; 

 and it is by no means impossible that some peculiar compound 

 of this substance may be formed, during the early stages of 

 decomposition, or even before death, which may, by its slow 

 combustion, give rise to the luminous appearance. It appears 

 that the whole substance of the body of the Fire-flies is phos- 

 phorescent ; for, according to an early historian of the West 

 Indies, "many wanton wilde fellowes" rub their faces with 

 the flesh of a killed fire-fly, "with purpose to meet their 

 neighbours with a flaminge countenance." 



Animal Heat 



403. One of the conditions necessary for the performance 

 of Vital action, is a certain amount of warmth ; and we have 

 seen that the animals which alone are capable of retaining 

 their activity in the coldest extremes of temperature, are those 

 which have the power of generating heat within themselves, 

 and thus of keeping-up the temperature of their bodies to a 

 high standard. Those which do not possess a power of this 

 kind, are either rendered completely inactive, even by a com- 

 paratively moderate cold, or are altogether destroyed by it. 

 Those which ordinarily do possess this power are destroyed 

 even more rapidly by cold, if from any cause the production 

 of heat within their bodies be interrupted ; for they are the 



