414 Dr. J. H. Pring's Observations atid 



to be expected that those forms of animal life, whose very ex- 

 istence was held to be problematical, should themselves be 

 made the subjects of actual experiment; and it is accordingly 

 among those more undoubted and eas>iiy accessible examples 

 afforded by the insects to be found on the land, that the study 

 of the phaenomena of vital phosphorescence has been chiefly 

 prosecuted ; the glow-worm and the fire-fly having been 

 generally selected for the purposes of experimental investiga- 

 tion, from the period in question even down to the present time. 



Thus, in the second edition of Chaptal's Chemistry, pub- 

 lished so long since as the year 1795, we read that " Mr. 

 Forster of Gottingen found that the light of glow-worms is 

 so beautiful and bright in oxygenous gas, that one single in- 

 sect was sufficient to afford light to read the Armo?ices Savantes 

 of Gottingen, printed in very small character." The same 

 fact is likewise referred to, and ably commented on, in an 

 excellent paper on the phosphorescence of the Luciole {Lam- 

 pyris Italica) by Dr. Carradori, in the second volun)e of Til- 

 loch's Magazine; and similar notices are thus incidentally to 

 be met with interspersed throughout the mass of physiological 

 and chemical writings with which science is now enriched. It 

 is, however, to Professor Matteucci that we are indebted for 

 the most accurate and comprehensive experiments that have 

 hitherto been undertaken in connexion with this department 

 of inquiry ; and although still confined principally to the glow- 

 worm, his observations may fairly be assumed to afford the 

 best exposition of the existing state of knowledge on the sub- 

 ject of phosphorescence now extant; and I must accordingly 

 refer to his valuable lectures, as published by Pereira, all 

 those who may be desirous of becoming acquainted with the 

 minute structure of the phosphorescent organs of the glow- 

 worm, and such other topics as do not appear to fall strictly 

 within the design of the present paper. 



On comparing the results obtained from the action of va- 

 rious gases on the Noctiluca, as described in a former part of 

 this communication, with the effects produced by the same 

 agents upon the glow-worm as recorded by Professor Mat- 

 teucci, some very remarkable differences will be found to pre- 

 sent themselves to our observation. It is right, however, to 

 bear in mind the different circumstances under which the ex- 

 periments are necessarily conducted in the two instances; the 

 animalculae in the former, being brought into contact with the 

 gas only through the medium of the water in which they float; 

 whereas in the case of the glow-worm, the insect is freely and 

 entirely exposed to the gas in which it is immersed. 



Bearing in mind^ then, and making suitable allowance for 



