Animal Luminescence 545 



ceptible that they give this light when they swell a little, and inhale 

 the air." 



The display of synchronous flashing is not confined to Siam but 

 is particularly striking there, and has been observed by many later 

 travelers, such as Bishop Pallegoix (1854) ; also Sir John Bowring 

 (1857) , who wrote: 



They have their favorite trees, round which they sport in countless multi- 

 tudes, and produce a magnificent and living illumination: their light 

 blazes and is extinguished by a common sympathy. At one moment every 

 leaf and branch appears decorated with diamond-like fire; and soon there 

 is darkness, to be again succeeded by flashes from innumerable lamps 

 which whirl about in rapid agitation. 



The mechanism of flashing and particularly the cause and mean- 

 ing of the remarkable synchronism is a problem still awaiting solu- 

 tion today. 



EIGHTEENTH-CENTURY RESEARCH 



During the eighteenth century glowworms and fireflies were in- 

 cluded in all the natural histories and attempts ^vere made to clear 

 up the development, habits, method of flashing and the nature of 

 the light. Many of the earlier beliefs were collected in the Samm- 

 lung von Natur und Medezin, sowie auch hierzu Gehoringen Kunst 

 und Literaturegeschichte so sich in Schlesien (1718 and 1724) by 

 Johann Gunther (1695-1723) , a poet and naturalist of Silesia, 

 eulogized by Goethe. 



Several pages are devoted to " De Cucujo " and " De Cicindela " 

 in the fifth part of Theatrum Universale Omnium Animalium 

 (Amsterdam, 1718), by Heinrich Ruysch (died 1727), and a very 

 small figine (plate 15) of a glowworm accompanies the text, but 

 there is little new to be found in the account. The treatment of 

 cicindela by Antonio Vallisnieri (1661-1730) in the third volume 

 of Opera Fisico-Mediche (Venice, 1733) also contains nothing new. 

 Vallisnieri did remark that further research was necessary to find 

 out " if they [a winged and wingless pair] copulate from mere desire 

 for a sexual act, ^vhether by their very nature they try to fecundate 

 the wingless, or if the wingless ones alone are females and the winged 

 are males, but I have not the leisure to make further research." 



John Hill (1716-1775) included the glowworm (without a figure) 

 under the name " Cantharis " in his History of Animals (London, 

 1752) , describing the male as a small black beetle and the female as 

 the glowworm with no wings, but " the last three joints of the body 

 are of a yellowish colour on the under surface and these appear 

 ignited or flaming in the dark." The glowworm is not mentioned as 



