314 
ON THE LIGHT-EMITTING- APPARATUS OF THE 
GLOWWORM. 
BY HENRY FRIPP, M.D., 
PRESIDENT OF THE BRISTOL NATURALISTS’ SOCIETY. 
T HE luminosity of animal matter must have been a familiar 
sigbt to man from the earliest ages. For then, as now, 
the valleys and plains which were the first dwelling-places of 
the human race, the great rivers which penetrated the interior 
of the country, and the seas which washed the coasts, teemed 
with animal life. The extraordinary spectacle of a luminous 
sea certainly could not have escaped observation, however igno- 
rant the observers may have been at that time of its cause. Yet 
so long ago as the beginning of the Christian era, the great 
Roman naturalist Pliny was acquainted with the shining pro- 
perties of the gelatinous medusae. And nearly four centuries 
before, Aristotle had described the evolution of light from putre- 
scent matter, and the light- emitting faculty of the living glow- 
worm. In our time the number of known species of marine 
invertebrates endowed with luminous faculty exceeds one 
hundred, and the number of land animals known to possess 
this power is also considerable. The latter belong chiefly to 
the invertebrate kingdom, and notably to the classes of insects 
and myriapods. But instances of occasional luminosity are 
not wanting amongst the superior animals, and even in indi- 
viduals of the human species. In such cases, however, the 
production of light appears to be dependent upon disturbance 
of the electric state of the tegumentary organs, and so far as 
it has been observed in man, upon abnormal conditions of the 
nervous and digestive systems. 
The word “ phosphorescence,” commonly accepted as ex- 
planatory of this curious phenomenon, does not well accord 
with the revelations of modern science. As we even now 
speak of “ lucifer matches,” so the alchemists of old borrowed 
a name for the non-metallic element whose luminous pro- 
perty is so remarkable, from Phosphor, the morning star, 
and symbol of brightness. In course of time the word was 
applied to all phenomena of the kind, whether exhibited by 
minerals, plants, or animals. The study of phosphorescence, 
