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



in some form of combination was deemed necessary to the 

 display of the luminous property, and in fact that this sub- 

 stance was regarded as the essential ingredient entering into 

 the composition of the phosphorescent matter. Thus it is 

 stated by Carradori, " Behind this receptacle is placed the 

 phosphorus, which resembles a paste having the smell of 

 garlic, and very little taste*." Again, we find Chaptal 

 speaking of it without any hesitation as a phosphoric oil. 

 After noticing the solubility of phosphorus in oils, and more 

 especially in the volatile oils, he observes, " The combina- 

 tion of phosphorus and oil appears to exist naturally in the 

 glow-worm, Lampyris splendidula, Linnaei. Forster of Got- 

 tingen observes that the shining matter of the glow-worm is 

 liquid. If the glow-worm be crushed between the fingers, the 

 phosphorescence remains on the finger f." 



More recently, again, we find Miiller enumerating several 

 facts bearing on the subject, and deducing from them the fol- 

 lowing conclusion : — " From all the above facts, the opinion 

 of Treviranus appears most probable; namely, that the light 

 is derived from a matter containing phosphorus, which is 

 formed under the influence of light, but, once formed, is in 

 some measure independent of light J." Nor am I indeed 

 aware that this notion of the actual presence of phosphorus 

 in the phosphorescent matter of living beings, has ever, pre- 

 viously to the observations of Matteucci, been entirely re- 

 jected. 



After detailing the influence of the various reagents em- 

 ployed in an elaborate chemical examination of the phospho- 

 rescent matter, Matteucci observes respecting it, — " It does 

 not present any obvious trace of phosphorus ; of this fact I 

 have assured myself by calcining this matter several times in 

 a platinum crucible, and by treating the dissolved residue with 

 the tests which indicate the presence of the phosphates. From 

 all we have now stated, we can no longer regard the presence 

 of phosphorus as the cause of the light in these insects^;" 

 and in another place, as before mentioned, it is said to be " a 

 substance, sui generis, principally composed of carbon, hydro- 

 gen, oxygen and azote." 



On a point like the present, however, where the statement 

 just mentioned is so entirely in opposition to all previous ob- 

 servation, it would seem desirable that we should know with 

 certainty what is the smallest possible amount of phosphorus 

 which is capable, when placed under the most favourable cir- 



* Tilloch's Magazine, vol. ii. p. 79. 



t Elements of Chemistry, vol. iii. p. 362. 



j Elements of Physiology, vol. i. p. 103. § p. 182. 



