26 CONCHOLOGIST’S COMPANION. 
entirely disappears when the milk which contains it 
is excluded from the air; but again revives on 
exposure to the atmosphere. In the exhausted 
receiver of an air pump, the Pholas loses its light. 
Various attempts have been made to render the 
light of the Pholas permanent ; for which purpose the 
juices of the fish were kneeded with flour into a kind 
of paste. This compound afforded a considerable 
degree of light when immersed in warm water: but 
the preservation of the fish itself in honey answered 
much better; as, by this method, the Pholas was 
kept for more than twelve months, and its lumious 
quality could at any time be restored by the appli- 
cation of warm water. 
Thus far are we indebted to the experiments of 
Reaumur and Beccarius. But the reason for this 
remarkable provision, as well as the purpose to 
which it is applied in the animal economy, are 
equally unknown. It is one of those extraordinary 
facts in natural history, which, like the playful 
meteors that often beautifully illuminate the solitary 
woods with their agile and wandering lights, repeatedly 
invite the traveller to an unsatisfactory pursuit, and 
as frequently elude his vigilance. 
The Greek word pholeus, from which the generic 
appellation of this extraordinary shell fish is derived, 
signifies, I lie concealed in a cave; therefore, Pholas, 
* 
