320 ZOOLOGY. 



rescence ; and it is probably to the presence of either 

 dead animal matter, or numerous microscopical creatures 

 that rapidly die, we must attribute the paradoxical 

 tendency to putrefaction which is so remarkable in sea- 

 water. It might naturally be supposed that, from its 

 chemical composition,, this fluid would long remain un- 

 changed when it was removed from the ocean ; but the 

 reverse is the fact, and a vessel of sea- water, kept but for 

 a few hours in the climate of the tropics, becomes highly 

 offensive, while the same quantity of perfectly fresh 

 water, under the same circumstances, does not undergo 

 the slightest alteration. The same fact may also inform 

 us, why marshes which receive a portion of their waters 

 from the sea, are invariably more injurious to the 

 health of man than those which are supplied by fresh 

 water alone. 



It is essential that the nautical naturalist should not 

 be misled by the phosphorescent appearance of a dead 

 marine animal, nor consider that any sea-creature is 

 naturally luminous, unless tokens of its vitality are in- 

 disputably present : for it is remarkable of the vital 

 phosphoric quality existing in fishes and molluscs, that 

 it fades and ceases as the animal becomes more feeble 

 and dies a peculiarity which widely distinguishes the 

 true luminous property, from that cadaverous phospho- 

 rescent light which attends upon incipient decay. 



The evident existence of a phosphoric principle in 

 marine animals, whether as a vital or cadaverous 

 attribute, would appear to commence with fishes ; for 

 we do not find that living seals, whales, sea-snakes and 

 turtle, or the decaying structures of those ocean 

 animals, exhibit any phosphorescent light. On one 

 occasion, it is true, I observed the blubber removed 

 from a Cachalot shine for two successive nights, with 



