354 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 



3. THE EFFECT OF CHEMICAL REAGENTS, ETC., ON THE LUMINOUS 



TISSUE. 



During the summer of 1909 the writer was associated with Prof. 

 Joseph H. Kastle in a study of the effect of various chemical reagents 

 on the luminous tissue of Photinus pyrdlis.( 35 ) Prof. Kastle and 

 the writer tried the effect of a large number of chemical substances 

 upon the live insect, the freshly detached luminous organ, and the 

 luminous tissue which had been dried in hydrogen, and some of these 

 results seem worthy of special attention. Taking first the live 

 insect: Injections of solutions of the metallic nitrates, of strychnin, 

 and of adrenalin caused the emission of light. Immersion of the 

 insect in methyl and ethyl alcohols, in ether and in chloroform, 

 resulted in the production of light. Immersion in pure oxygen 

 appeared to stimulate the photogenic function somewhat, but not 

 as much as might have been expected. Immersion in nitrous oxide 

 caused a considerable increase in the intensity of the light. In 

 the cases of injection and immersion in liquids, the reagents kill the 

 insect, but not until they have caused light emission. Nitrous 

 oxide narcotizes the insect, but in the air it recovers again. Hydro- 

 cyanic acid and cyanogen kill the insect, of course, but not until they 

 have caused the emission of light. The luminous organ of one of 

 the local species of Lampyrida has been observed to glow in the 

 mixture of air and prussic acid in the cyanide killing bottle for over an 

 hour, long after the actual death of the insect. Ammonia water 

 causes the evolution of light either by injection or immersion; 

 Watase is authority for the statement that if a tissue suspected of 

 being luminous refuses to give light with any other stimulus, it will, 

 if a true photogenic tissue, glow on moistening with dilute ammonia 

 water. The injection of 3 per cent hydrogen peroxide solution also 

 caused the evolution of light. Lund ( 42 ) has also studied the effect 

 of H 2 2 on the tissue. 



With the freshly detached luminous segments, the most notable 

 results were obtained with the vapors of methyl and ethyl alcohols, 

 carbon tetrachloride and bisulphide, and mononitrobenzene acting in 

 the presence of air. All of these reagents caused light emission and 

 the light given out was not the continuous faint glow frequently the 

 result of weak chemical stimuli, but was accompanied by a series of 

 distinct flashes or pulsations of light similar to the normal flashes 

 of the insect. With the detached organ, the effect of powerful 

 poisons was in almost every instance to produce the evolution of 

 light, sometimes faint and of short duration, but definite. As 

 examples of poisons acting thus may be cited hydrofluoric acid, iodine 

 cyanide, and bromine. 



