304 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 pyralis.() 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 Lampyride 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; 
Watasé 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 (*) has also studied the effect 
of H,O, 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 
hight, sometimes faint and of short duration, but definite. As 
examples of poisons acting thus may be ee aes sons acid, iodine 
cyanide, and bromine. 
