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ANATOMY AND PHYSIOLOGY 
influence by checking respiration in the way in which 
it causes the nerve to act upon the muscle in muscu- 
lar motion."* 
These remarks appear to harmonise with the prin- 
cipal facts which have been ascertained respecting 
this interesting phenomenon, and the nature of the 
substance by which it is produced. These facts are 
chiefly the following: — the light is subject to the 
will of the animal ; it becomes more brilliant when 
its motions are violent ; a certain degree of heat is 
necessary for its display, and its intensity increases 
up to 40° R. when it becomes extinct, as it likewise 
does when the cold is at 10° R. ; oxygen renders it 
more brilliant for a short time, but soon extinguishes 
it ; the same effect is produced more speedily by irres- 
pirable gases, and by placing it in a vacuum ; the 
phosphorescence soon disappears after the death of 
the animal, but can be restored by warm water, oil, 
or alcohol ; galvanic electricity excites it ; and, finally, 
when the insect is kept for some time in the dark, 
the luminosity disappears, but is restored by exposure 
to the light of the sun. 
According to the observations of M. Morren, pro- 
fessor of botany in the University of Liege, as detailed 
by Lacordaire, the luminosity of the common Euro- 
pean Lampyridse is increased in brilliancy by the 
peculiar structure of the corneous envelope of the 
phosphorescent matter. It is stated to be merely a 
continuation of the general tegument, become much 
* Burmeister’s Manual of Ent. p. 497. 
