PHOSPHORIC INSECTS. 139 
Matteucci has made a number of experiments 
upon Lampyris italica, 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. Ro- 
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 Stvivs—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, z.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 /wminous 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.) 
