OF INSECTS. 
171 
posed of albumen. But as albumen is not luminous 
of itself, it must be combined until a certain propor- 
tion of phosphorus, in order to produce the phenome- 
non in question. “ As phosphorus can only become 
luminous by contact with oxygen, if we imagine*it 
combined with the fatty substance, or with its albu- 
men, respiration gives it luminousness ; by means of 
respiration, oxygen is deposited in the corporeal sub- 
stance, and each respiration therefore makes the 
beetle shine. Now, respiration being strongest during 
flight, it necessarily follows, that the emission of light 
will also then be most powerful. In opposition to 
this, the wingless state of the female might be urged, 
yet her short thicker body must contain more of the 
fatty substance, and must therefore emit a stronger 
light than that of the male. Next to respiration, the 
circulation of the blood appears to have considerable 
influence upon the light, for we know that the sub- 
stance emits the light only when moist. As now, 
the blood flows all round upon the fatty substance, 
this may be considered as the moisture, which helps 
to support the luminousness. Caras has also observed 
that upon each pulsation, and consequently upon each 
fresh wave of blood, the light shines brighter. He 
refers to this, also, the brighter shining of the female, 
as she constantly dwells in dark damp places. Third- 
ly, the nervous system may exercise a certain influence 
upon the production of the light ; for as it is the chief 
agent of all the voluntary actions of the body, it will 
also necessarily exercise an influence upon the volun- 
tary suppression of the light, if the insect stop this 
