664 Fire-Flies and their Phosphorescent Phenomena. {October, 
A calcium sulphuret of phosphorus, prepared by heating sulphur 
with calcined oyster shells, is said to give out a yellow light when 
exposed to the sun’s rays, but under decomposed light there is a 
change to green. The decomposition of certain rocks furnishes 
phosphates of calcium to the soil, whence having been appropriated 
by plants it eventually supplies animals. When not oxidized in the 
stomach it is supposed to be absorbed into the system in certain 
oils. Phosphorus in its active state ignites spontaneously in con- 
tact with the air. 
In Lampyris we see changes identical with those presented by 
a calcium sulphuret of phosphorus from the red or yellow to green. 
The emission of the greatest amount of light would also point 
to the presence of phosphorus, this occurring most freely in the 
open air, and when the insect is either flying or excited, when the 
body is presumed to be most fully inflated with air, the spiracles 
on the luminous segments being very favorable for its admission. 
The second light, referred to as of a milder kind and with a 
steadier emanation, would seem to be portions absorbed by the 
translucent substance during the more active evolution of light, 
and reflected from the less permeable inner o of the dorsum 
until exhausted. 
The uses of the light of Lampyris seem as doubtful as its 
nature. As it cannot be of service in the larval state either for 
sexual attraction or to secure food, its presence at this early period 
must be for the benefit of succeeding stages, and especially for 
the imago in the case of the apterous female.. 
he periodicity of the phenomenon may be ascribed to that 
_ property of the ganglia which enables them to give a periodical 
exhibition of an original disturbing cause. 
There is a definite relation between the proportion of light 
emitted, and the color of the enclosing membrane which indicates 
the former’s bleaching power. 
Draper illustrating a truth says, that “ not a shadow falls for an 
instant upon a wall but it leaves an ineffaceable stain,” thus by 
his shadows bringing the power of light into bold relief. If a 
ray of light falls, however softly and but for an instant, upon an 
object, we may presume that a change, whether by chemical or 
_ mechanical means, ensues. Flowers and fruits by their irregular 
_ surfaces break the sunshine into specific hues, thus acting as 
- shadows to themselves. Animals also respond in coloring to the 
influence of tight, 
