580 History of Luminescence 



they lived to Bologna in 1724. Unlike Reaumur, they had better 

 luck in preserving the light. Priestley (1772: 567-569) has given the 

 account: ** 



Beccarius observed that, though this fish ceased to shine when it be- 

 came putrid, yet that, in its most putrid state, it would shine, and make 

 the water in which it was immersed luminous, when they were agitated. 

 Galeatius and Montius found that wine or vinegar extinguished this 

 light, that in common oil it continued some days, but in rectified spirit 

 of wine, or urine, hardly a minute. . . . 



Of all the liquors to which he put the pholades, 7nilk was rendered 

 the most luminous. A single pholas made seven ounces of milk so lumi- 

 nous, that the faces of persons might be distinguished by it, and it looked 

 as if it was transparent. 



Air appeared to be necessary to this light; for when Beccarius put the 

 luminous milk into glass tubes, no agitation would make it shine, unless 

 bubbles of air were mixed with it. Also Montius and Galeatius found 

 that, in an exhausted receiver, the pholas lost its light, but the water was 

 sometimes made more luminous; which they ascribed to the rising of 

 bubbles of air through it. 



Beccarius, as well as Reaumur, had many schemes to render the light 

 of these pholades permanent. For this purpose he kneaded the juice 

 into a kind of paste, with flour, and found that it would give light when 

 it was immersed in warm water; but it answered best to preserve the fish 

 in honey. In any other method of preservation the property of becoming 

 luminous would not continue longer than six months, but in honey it 

 had lasted above a year; and then it would, when plunged in warm 

 water, give as much light as ever it had done. 



The Italians and the French have always been most impressed by 

 Pholas and its light. Fougeroux de Bondaroy published a memoir 

 on the " datte " in 1768, with a fine drawing of the appearance in 

 rock. J. Barbut (1783) also mentioned the light in his Genera Ver- 

 miorum (1783) . An excellent dissection of the animal itself, show- 

 ing for the first time all five luminous regions was published by 

 Josepho Xaverio Poli in 1791. 



Modern study of the luminescence began in 1872 with Paolo 

 Panceri, whose work on histology led him to discover the granules 

 connected with light emission. Pholas bears a special claim to fame 

 as the animal used by Raphael Dubois in many biochemical experi- 

 ments. In 1887 he introduced the terms " luciferine " and " luci- 

 ferase " for the substances involved in light production and pub- 



■•* The article in the Com)nen. Acad. Bonon., " De luce dactylorum," 2 (I) : 248-273, 

 1745, was not signed. It was a joint work of a number of the Academicians, chiefly 

 Beccari, Monti, and Galeati. It has been fully described in French in Collection 

 Academique Etranger 10: 127-150, 1773. 



