162 EDIBLE BRITISH MOLLUSKS. 



eaten, they give forth their light, and the same, too, 

 when in the hands: the very drops, in fact, that fall 

 from them on the ground, or on the clothes, are of the 

 same luminous nature."* 



Dr. Coldstream states that "the phosphorescent light 

 of this mollusk is given out most strongly by .the in- 

 ternal surfaces of the respiratory tubes, and that it is 

 strongest in summer; and Professor John Mulier has 

 observed, that when Pholades are placed in a vacuum, 

 the light disappears, but reappears on the admission of 

 air; also, that when dried, they recover their luminous 

 property on being rubbed or moistened. "f 



Many others have also made experiments with the 

 Pholas, and have studied its phosphorescence, viz. Reau- 

 mur, Beccaria, Marsilius, Galeatus, and Montius. The 

 two first mentioned endeavoured to render this " lumi- 

 nosity permanent, and the best result was obtained by 

 placing the dead mollusk in honey, by which its pro- 

 perty of emitting light lasted more than a year. When- 

 ever it was plunged into warm water, the body of the 

 Pholas gave as much light as ever." J 



Beccaria also found that a single Pholas rendered 

 " seven ounces of milk so luminous that the faces of 

 persons might be distinguished by it, and it looked as if 

 transparent." § 



Pholas dactylus, or the long oyster, as it is called at 

 Weymouth, is not often eaten in England, but is gene- 

 rally used for bait. A Newhaven fisherman, however, 

 told me they sometimes collect some for eating from 



* Pliny, Nat. Hist. vol. ii. bk. ix. c. 87. 



f Forbes and Hanley, vol. i. p. 107. 



+ ■ Phosphorescence,' by T. L. Phipson, Ph.D., F.C.S., p. 105. 



§ Ibid. p. 104. 



