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so in less than one -fourth of that period. This last 

 experiment proves, that though the luminous matter 

 may, when undisturbed in its capsule, remain even 

 for hours luminous, it is volatile and subtile when its 

 containing membrane is lacerated or destroyed. The 

 corrosive medium, even of a solution of nitromuriate 

 of platinum, could act only on the exterior wall, and 

 not affect the luminous matter imprisoned within its 

 confines. The yellow spherule, viewed by candle- 

 light in oil of olives, seems to be surrounded by a 

 cloudy atmosphere. When, from extreme cold, it had 

 ceased to be luminous in the dark, we held it im- 

 mersed in olive oil in a thin glass capsule in the warm 

 hand for five minutes, it then emitted a faint nebu- 

 lous light. This resembles the character of some of 

 those substances called solar phosphori ; for instance, 

 the chlorophane, of which we possess a specimen that, 

 held in the hand, evolves a fine green light. 



We are wont to contemplate light as associated 

 with the production of combustion, or the offspring 

 of chemical action ; but here is a light under a pecu- 

 liar form, and independent of chemical conditions. 

 The following appear to us corollaries deducible from 

 the preceding detail of experiments : 



I. Light, as connected with the glow-worm, is a 

 subtile evanescent material principle, perhaps con- 

 nected with a peculiar organised structure, circum- 

 fused round the vitellula of the ovum, or integrating 

 with it; unsupported by any chemical action, and 

 confinable by the transparent film, or capsule, which 

 imprisons it. 



II. This light is permanent, and independent of any 

 power possessed by the insect over it, except so far 

 as it can withdraw the luminous matter from the 

 window, or transparent medium through which it is 



