420 Dr. J. H. Pring's Observations and 



remarked, on the other hand, that when the sea-water is con- 

 verted into ice it still retains its luminous property. 



It now remains only to offer a few words with respect to 

 the 



Use of vital phospJwrescence, a subject, which, as it has 

 already proved the fertile source of a great amount of specu- 

 lation, more remarkable for its ingenuity than for any more 

 satisfactory result, it will be my endeavour to dismiss without 

 increasing the accumulated mass of conjecture with which it is 

 already encumbered. As the instances of vital phosphorescence 

 occur amongst so varied and wide a range of the animal crea- 

 tion, it is only reasonable to infer, that in different individual 

 instances this faculty will serve respectively a different pur- 

 pose. Thus in the highly predaceous luminous shark, the 

 SqualusJulgenSf formerly noticed, it may readily be assumed 

 with Mr. Bennett*, "That the phosphorescent power it pos- 

 sesses is of use to attract its prey, upon the same principle as 

 the Polynesian islanders and others employ torches in night 

 fishing." In the insect tribe, again, it has no doubt been 

 correctly described as furnishing " a la lettre, le flambeau de 

 I'amour." 



Amongst the lower marine tribes, however, the object of 

 this luminous provision is generally admitted to be much less 

 apparent ; and the most probable conjectures that have been 

 formed respecting it, are those by which it is regarded as an 

 engine of defence. Mr. Kirby appears to have viewed it alto- 

 gether in the latter light; upon which Mr. Bennett has the 

 following remark : — " I cannot believe, with Mr. Kirby, that 

 it serves as a mode of defence; because from what we know 

 of the nature of fishes, this refulgence would be one of the 

 surest means of bringing their probable enemies upon them ; 

 and if we are to regard the oeconomy in a destructive point 

 of view, we might rather suppose that it is intended to direct 

 the nocturnal predaceous fishes to their food. * * * But it 

 would be unjust to accuse Nature of thus wantonly investing 

 her creatures with a charm that can only tend to their destruc- 

 tion f." The train of argument here employed may be cited 

 as an example of the uncertainty and perhaps error into which 

 the mind may be betrayed, when it quits the plain and sober 

 path of reason, to wander in the field of mere conjecture. 



In the instance of the Noctiluca, as already hinted, and for 

 the reasons formerly assigned, it seems probable that this 

 luminous property serves the purpose of defence; though whe- 

 ther this is its sole object, is a question for future investigation 

 to determine. 



• Vol. ii. p. 258. t Vol. ii. p. 325. 



