550 History of Luminescence 



in them, but it is sooner extinct in alcohol than in Avater. Heat forces 

 out a bright glow, and then it becomes extinct; but if not carried too 

 far. the addition of moisture after a time revives its poAver. No motion 

 or mixture seems to destroy its power whilst it remains fresh and moist, 

 but yet a portion thus rubbed, sooner lost its light than a portion left 

 untouched. 



It is to be regietted that in the long period following this early 

 ^\-ork Faraday did not further pursue luminescence studies. 



Tlie most complete paper on fireflies ^vas that of Issac Francois (J.) 

 Macaire (1796-1869) , a professor of the Academy at Geneva, much 

 of it reviewed by Tweedy John Todd, M. D., in 1824 and 1826, 

 whose OAvn conclusions ascribed the light to " vital action." Macaire's 

 studv of electricitv and galvanism ^vas the first to be made \\'ith glow- 

 worms (Lampyris noctiluca and L. splendidula) . Under the head- 

 ing " I'electricite," Macaire reported no effect from an electrical 

 machine or Levden jar. Even Ashen a spark struck the insect it did 

 not gloAv but imder the heading " du galvanisme " he fotnid that the 

 voltaic stream from a pile did have an effect. 



Although other Avorkers had noticed that the light disappeared 

 at a high temperatiu-e, Macaire made a special study and concluded 

 that a certain temperature range was necessary for the voluntary 

 lighting of the glowAvorms and that too great heat prevents even 

 the luminous matter to shine. The light intensity increased to a 

 temperature of 33° R, then decreased in intensity and went out 

 with a definite red color at 42° R. Apparently Macaire was the first 

 to note the reddish tinge of firefly light just before it is extinguished 

 at high temperatures. He also noticed that all agents (acids, alcohol, 

 heavy metals, etc.) As'hich coagulate albimien put out the light, and 

 concluded that the luminous matter Avas principally albumen in a 

 transparent state w^hich becomes opaque on coagulation. The lumi- 

 nous material "was not soluble in oils, either hot or cold, or in 

 alcohol, as is phosphorus. Macaire's experiments led him away from 

 the older idea that the luminous material was either phosphorus 

 or a derivative of phosphorus, a very important concept. 



SomeAvhat similar conclusions to those of Macaire Avere obtained 

 in 1843 from a study of the Italian lucciole (Lampyris Italica) by 

 Carlo Matteucci (1811-1868), professor in the University of Pisa. 

 His final conclusions were collected in a chapter of his book, trans- 

 lated into English as Lectures on the Physical Phenomena of Living 

 Beings, London, 1847. In addition to studying behavior in various 

 gases which indicated that an oxidation Avas involved in light pro- 

 duction, Matteucci claimed to have established the fact that Ashen 

 oxygen is used by the phosphorescent matter, a corresponding 



