posed of albumen. But as albumen is not luminous of itself, it must be combined with a certain proportion of phosphorus, in order to produce the phenomenon in question. "As phosphorus can only become luminous by contact with oxygen, if we imagine it combined with the fatty substance, or with its albumen, respiration gives it luminousness; by means of respiration, oxygen is deposited in the corporeal substance, 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 substance 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. Thirdly, 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 voluntary suppression of the light, if the insect stop this
