Animal Luminescence 543 



For the sake of those learned men, that have thought the light of glow- 

 worms and other shining insects to be a kind of effulsion of the bio- 

 lychnium, or vital flame, that nature has made more luminous in these 

 little animals than in others ... we took two glow-worms . . . these we 

 laid upon a little plate, which we included in a small receiver of finer 

 glass than ordinary . . . and as we expected, upon the very first exsuction 

 there began to be a very manifest diminution of the light, which grew 

 dimmer and dimmer, as the air was more and more withdrawn, until 

 at length it quite disappeared, though there were young eyes among the 

 assistants. This darkness having been suffered to continue a long while 

 in the receiver, we let in the air again, whose presence as we looked for, 

 restored at least as much light as its absence had deprived us of. 



Thinking that the disappearance of the light might be due to 

 some reaction of the whole animal, in the next experiment Boyle 

 repeated the effect of the vacuum on a glowing excised light organ 

 and foimd that its luminescence also disappeared. These experi- 

 ments served to establish the similarity of the light of shining wood, 

 fish and insects. They supplemented his observations that flames 

 cannot exist in a vacuum, that the light of burning sulphur, cam- 

 phor, or alcohol quickly disappears. He found in fact that an alcohol 

 flame went out before a small bird (a green finch) showed signs of 

 being affected by the lack of air. The experiments were an early 

 demonstration of the necessity of something in the air for living 

 things and burning bodies and clearly placed the luminescence of 

 organisms in the same category. 



MARCELLO MALPIGHI AND THE ITALIAN FIREFLY 



Of all the seventeenth-century writers, Marcello Malpighi (1628- 

 1694) was the most painstaking in his study of fireflies.^ His account 

 is given by F. S. Bodenheimer (1928: 1: 337) , who has quoted from 

 unopened note-books ^ of Malpighi in the University Library at 

 Bologna. Malpighi wrote (30 Maggio, 1688) concerning " De Cicin- 

 dela " as follows: 



The end of the body cavity, the last two segments, contains a fluid which 

 is the source of the light. In daylight it appears yellowish and contains 

 a milky substance. In the dark it lights sulphur yellow. The fluid con- 

 tains a mass of small yellow globules in a similar slimy substance, which 

 is half fluid. The beetle lights at night and in the dark from both hind- 



^ Although F. Redi (1626-1697) studied the metamorphosis of many insects, he did 

 not investigate the lucciole, nor is its development considered in J. Godart's Metamor- 

 phosis el historia naturalis insectorum, etc., 3 v., 1662-1667; in English, 1682. 



* These notes have been published by G. Atti as Notizie edite ed inedite della vita e 

 della opera di Marcello Malpighi, Bologna, 1847. 



