OF INSECTS. 171 



posed of albumen. But as albumen is not luminous 

 of itself, it must be combined with 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. Carus 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 



