578 History of Luminescence 



mouths of persons eating them " and the mention of their lumi- 

 nescence by naturalists of the sixteenth century, Wotton, Belon, 

 Rondelet, Boussuet, Aldrovandi, Gesner, and Olaus Magnus, early 

 served to direct attention to these remarkable boring molluscs. They 

 were called dactyli (fingers) , solenes ^^ (pipes) , balani (dates) or 

 pholades (lurking in holes) in Latin. ^^ Despite a life within a shell 

 in a hole in the rock or hard mud, the animal nevertheless pro- 

 duces an abundant luminous secretion whenever disturbed (see 

 fig. 2) . 



During the seventeenth century the luminescence of Pholas was 

 mentioned by Jonston,^^ Zucchi,^^ Kircher,^^ Schott,*° Bounanni,*^ 

 and other writers. The light-emitting ability was doubted by Bar- 

 tholin, as he never happened to have seen the animal alive; and 

 considered Pliny's accoimt a phantasy. Nevertheless, Bartholin re- 

 ferred to Olaus Magnus and Kircher's statements and quoted a poem 

 of Lippius *^ speaking of the luminescence. 



The dactylus illuminates with beaming light the sea 

 When he is put on the table, the table glitters with light. 



For some reason pholads never came to the attention of Boyle and 

 his companions in the Royal Society, despite the abundance of the 

 piddock along the English coast, and Martin Lister {ca. 1638-1711) , 

 the great English conchologist, did not stress the luminescence.^^ 



^^ Reaumur (1723) has stated that Rondelet, Aldrovandi, Gesner, Jonston, and all 

 early naturalists have confused Solen, the " coutelier " (cutler) or " couteau " (knife) 

 with the dail, Pholas dactylus. He found the former not to be luminous, whereas the 

 latter was luminous. Pliny had described Pholas under the names, Solen, Aulos, Donax, 

 Onix, and Dactylus. Dactylus is the preferred name. Both the coutelier and the 

 dail or dactylus (Pholas) are figured on plates 6 and 7 respectively of Reaumur's 

 (1712) article on the movement of some marine molluscs. 



^' The commonest rock-boring molluscs of the Mediterranean and Atlantic coasts 

 of Europe are Pholus dactylus, Pholas crispata, and Lithodomus lithophagus, to which 

 the modern Italian, datolo, dattilo, datero, or the French, datte de mer and dail, are 

 applied. Lithodomus does look like a date. Only P. dactylus is markedly luminous, 

 but all are edible. There are many local French names, such as dague, gite, picot, 

 pitot, pitant, pitan, dedan, derte, collected in Eugene Rolland's Faune populaire de 

 France 3: 221, and vol. 12: 79, Paris, 1881. The English name is piddock or piddick. 



" Historia nattiralis, de exsnnquibns aquatis, libri IV, Francofurti, 1650. 



^^ Philosophia optica, 48, Romae, 1652-1656. 



^^ Ars tnagna lucis et umbrae, lib. I, part 1, chap. 7, 1646. 



*° Physica curiosa. Append, lib. XII, cap. 4, p. 1372. 



*^ Bounanni in Recreatio mentis (1684) and Museum Kircheranum (1709) . See 

 Chapter IV. 



*' Translated by Mrs. Annemarie Holborn. The author is probably Lorenzo Lippi 

 (1606-1664) , artist and poet. 



*' Sir Robert Sibbald (died 1712) published an excellent figure of Pholas in his 

 Scotia illustrata (1684) , on the natural history of Scotland, without mentioning the 

 luminescence of the animal. 



