THE CHEAPEST FORM OF LIGHT. 19 



Insects" (Proc. Am. Soc. Micros., 14th meeting), in which he claims 

 that the emission of light by these insects is connected with the process 

 of oxidation. He says: "In several species of luminous insects the 

 structure of the photogenic organs is specially adapted to secure the 

 most copious supply of air throughout the substance of the gland," and 

 he concludes that this peculiar structure is to enable the glands to pro- 

 duce light by the action of oxygen, the energetic princii)le of the air. 



Lophin (C.^iHjgNJ exhibits this phenomenon at the low temperature of 

 10° C, in the presence of oxygen and alkalies. 



The identity of the light from living beings and that from carbon 

 compounds has been established by spectroscopic observation. The 

 caustic alkali, which is incompatible with organic life, can be replaced 

 l)y cholin, neurin, and other bodies that are known constituents of living 

 beings. 



The quantity of these materials required to produce light is very 

 small ; 1.82 grams of lophin dissolved in 25cc. strong alcoholic i)otash 

 gave light for 20 days throughout its entire mass. 



The Russian experimenter extracted with ether from the bodies of 

 180 Pelagia noctiluca a thick yellow liquid that shone beautifully on 

 shaking with an alkali. 



In 1893 Raphael Dubois,* whose monograph, " Les Elaterides lumi- 

 neux " (Bull. Soc. Zoolog., 1886) has been cited, published a paper re- 

 cording his observations on a myriapod from Algeria, Oi-ya barbarica 

 (C. R., cxvii, 184). He confirmed the statement of M. Gazagnaire, who 

 had observed (in May, 1888) that the phosphorescent substance is secreted 

 by these insects on the sternal and episternal plates as a yellowish 

 viscid liquid. The excretion is distinctly acid, a fact that disproves, he 

 says, the oxidation theory, and he gives to the substance the name 

 " luciferine." 



Peter Schmidt, of St. Petersburg, published a paper in Russian " On 

 the luminosity of Midges," which was reproduced in 1895, in the Annals 

 and Magazine of Natural History (series 6, vol. 25, p. 133). Schmidt 

 divides luminous insects into two classes : A, those provided with special 

 luminous organs, and, B, those having luminous micro-organisms living 

 upon them. He places midges in the latter group. 



In 1896 H. Muraoka examined lampyrid beetles collected in Kyoto, 

 Japan, and found they emitted both actinic and Rontgen rays ; he noted 

 reflection of the rays, but was unable to determine refraction, inter- 

 ference, and polarization. Muraoka found the entire body actinically 

 active, and to increase the light sprinkled the insects with water ; he also 

 observed that the dead beetles were luminous when kept moist and when 

 rubbed. (Wied. Ann. Phys., vol. 59, p. 773.) 



* See also paper by Dubois on Physiological Light in Smithsonian Report for 



1895. 



