PHOSPHORIC INSECTS. 139 



Matteucci has made a number of experiments 

 upon Lampyris italic a, with a view of proving 

 that the phosphorescence of the glowworm is a 

 phenomenon of combustion ; and, however erro- 

 neous this opinion may hereafter appear, M. Ko- 

 berts had already professed it as the result of his 

 own experiments a year before M. Matteucci. 

 This part of my work is not devoted to the dis- 



of the solar spectrum ; twelve years afterwards Fraunhofer de- 

 termined the position of these lines, which are simply breaks or 

 interruptions in the coloured spectrum, with great accuracy. 

 Whenever light comes from the Sun, as solar light, as planetary 

 reflected light, as lunar light, or as light reflected from the clouds, 

 the number and position of these lines are the same. But when 

 light comes from other sources than the sun from other suns, for 

 instance, from the star Sirius these dark lines of the spectrum 

 differ. We find that the dark lines in the spectrum of Sirius 

 differ from those of Castor or from those of our Sun. This dif- 

 ference, which was first indicated by Fraunhofer, was afterwards 

 confirmed by Professor Amici, who also showed that in fixed 

 stars that have an equal and perfectly white light, the dark lines 

 are not the same. We also know that the specific character of 

 the source of light, i. e. its nature, has an influence upon these 

 lines of the spectrum. Thus the light of the electric spark and 

 that of incandescent solid bodies exhibit great diversity in the 

 number and position of Wollaston's dark lines. However inter- 

 esting the inquiry may appear, this knowledge has not yet been 

 applied to the light emanating from luminous animals, nor in- 

 deed to any phosphorescent substance in the strict sense of the 

 term. 



(Since the above was written, Kirchhoff, of Heidelberg, has 

 discovered that the dark lines of the solar spectrum are owing to 

 the presence of metals in the sun's atmosphere.) 



