170 KOLLIKER, ON LAMPYRIS. 
b. Acids —Very beautiful luminosity is produced by sul- 
phuric, nitric, and hydrochloric acids, and in the case of 
sulphuric acid, solutions containing from 75 to 75} per cent. are 
efficient for the purpose ; hydrochloric acid acted in solutions 
containing from 3 to 25 per cent.; mitric acid was tried, with the 
same result, in a solution containing 22 per cent., which was 
the only strength tried. The vapours, also, of the two latter 
acids act as excitants of the luminous organs. Besides these, 
a similar effect is produced by phosphoric, concentrated 
acetic, tartaric, citric, oxalic, and a five per cent. solution of 
chromic acid. 
(5.) Solutions of indifferent substances, in certain degrees 
of concentration, are also excitants of the luminous organs, 
such as the haloid salts and the neutral salts of the alkalies and 
earths, as well as sugar. Common salt acted as an excitant 
in solutions containing 3 per cent. and upwards, phosphate 
and sulphate of soda, in solutions of 4 to 5 per cent. 
d. Other excitants are alcohol of 45 per cent. and upward, 
anhydrous ether, creosote, lunar caustic, chloroform, and 
chlorine. 
e. No effect is produced by water, saliva, strychnia, dilute 
solutions of salts and acids, oils, sulphuret of carbon, and 
many metallic salts. Oxygen, also, from a single experi- 
ment, would not appear to be a true excitant, for separate 
abdomens, and entire insects not in a luminous state, fre- 
quently do not exhibit any luminosity until after one or 
several hours; but then, it is true, they shine long and 
brilliantly. 
14, The luminous property is destroyed by a great many 
influences, although it always exhibits great tenacity. It is 
always and speedily annihilated bythe mineral acids and caustic 
alkalies ; and also—a circumstance that appears to me of 
especial interest—by narcotics, which paralyse the nervous 
power, as by the fumes of hydrocyanic acid and of conein 
(experiments with the urara poison were unsuccessful). 
In the experiments made with these poisons, the 
animals under proper precautions for the protection of 
the experimentalist, were placed in a small watch-glass, 
and moistened with saliva; the watch-glass was then 
introduced into a larger vessel containing the poisonous 
vapour, so that the atmospheric air had free access. If 
the insects experimented on were in a luminous condition, 
the light was extinguished in from three to five minutes, and 
at the end of five to ten minutes the luminous organs were 
quite dead, and incapable of excitation by any means— 
crushing, electricity, and caustic alkalies. The same effect was 
