Luminous Animals. 255 



In the same seas, and nearly at all times, the water was found 

 filled with several different species, resembling in size some of 

 the infusoria, and invisible without the lens. To estimate their 

 numbers is equally impossible, but no body of water so small 

 could be brought into a proper situation without being found 

 filled with them. Other animals of larger dimensions, and of 

 many species were equally constant ; and, if less numerous, yet 

 ten or twenty were always to be found within the space of a 

 common tumbler glass. 



In all these cases the water was luminous ; and, that it was 

 rendered luminous by these animals, admitted of no doubt, 

 because the larger individuals could be taken out on a dry body, 

 shining at the very moment of their removal, and then replaced 

 for examination in water ; while the light of the whole of 

 these species disappeared when they died, either from keeping 

 the water too long, from warming it, or from the addition of 

 spirits. The facility with which the luminous quality of sea 

 water is destroyed by those means which kill its inhabitants, is 

 in itself a sufficient proof that the cause of this property resides 

 in these. 



I must further add, that it is perfectly easy to distinguish the 

 different sparks of light given by different animals ; that is, as 

 • far as they differ in dimensions ; as the bright spot is quite 

 distinct in the larger kinds, in which it also often varies in 

 colour ; while, in the smaller, agitation produces a general 

 luminous appearance, in which separate spots, or the distinct 

 action of individuals, is not to be recognised ; it is probably 

 therefore rather from this source, namely, the crowd of micro- 

 scopic worms and insects, that the general luminous track 

 produced by a fishing line, or the faint sheet of light elicited by 

 the dash of an oar, is caused, than by the detached secretions 

 of fishes, or by decomposing animal matter diffused through the 

 water ; while the brighter separate sparks arise from the larger 

 kinds, to the size of which they are more or less proportioned. 

 It will in the same way, be found, that the predominance of 

 bright sparks in the vicinity of sea weed, or near rocks, arises 

 from the great number of species, Squillise, Scolopendrw, 



