26 On the Phosphorescence of some Marine Invertehrata. 



phorescence arising from animal decomposition, nor of that 

 which results from mucus in a state of solution, I believe that 

 light is produced in living animals in two ways : — 



1st. By the secretion of a peculiar substance exuding either 

 from the entire body or from a special organ. It is probable 

 that in this first mode of phosphorescence the light always arises 

 from a slow combustion. The fact is proved as regards insects ; 

 but direct experiments are necessary before the same certainty 

 can exist as to marine Invcrtebrat a, Annelids, !Mollusks orRadiata. 



2nd. By a A-ital action, whence results the production of a pure 

 light independent of all material secretion. I had arrived at this 

 result at the time of the publication of my first note. My ob- 

 servations accord entirely with those that Ehreuberg made before 

 me ; yet doubts have been thrown out on the legitimacy of con- 

 clusions which we had both considered warranted by facts fur- 

 nished by observation alone. I hope that the experiments which 

 form the subject of the latter part of this memoir will reply to 

 all these objections. 



When I published my first note, I was informed of Ehren- 

 berg's results only through a conversation with Humboldt. I 

 have since consulted his memoir, and find that on some jjoints 

 we agree entirely, while we differ on others. 



With Ehrenberg I had learned to see in the phosphorescence 

 of the Annelids and Ophim'a which I have examined an action 

 essentially \'ital ; but I cannot regard this action as strictly con- 

 fined either to the organs or the functions of generation, as the 

 learned naturalist of Berlin considers it. I tind, it is true, in 

 renewing my notes, that one of the Pohjno'e which best exhi- 

 bited the phosphorescence was filled with zoospcrms in full 

 maturity, but many other Annelids among those which I have 

 studied were not in that state. Even in admitting that the light 

 uiaj^ be most brilliant at the period of gestation, I should regai'd 

 that fact as merely a coincidence arising from the increase of 

 vital energy which is thus very plainly manifested by all these 

 animals. Besides, in the Ophiura, the independence of the light 

 and the generative organs is very evident, since the sparks are 

 seen only along the arms, and the reproductive organs are en- 

 closed in the body, whose walls are very thick. 



M. Ehrenberg first made known the fact, that the phospho- 

 rescence of Annelids, &c., always results from a combination of 

 microscopic sparks. Here my observations accord entirely with 

 his. We have compared these httle flashes to those which are 

 px'oduced from a ' tableau fulminant ' which has been charged 

 from an electrical machine. 



But ]M. Ehrenberg has described in the Polynoe a special organ 

 for producing this hght. Here we differ. In the Pohjno'e, as 



