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phraseology this opinion amounts to the hypothesis of organic 
assimilation, by which the nutritive act stores up certain ele- 
ments of food capable of evolving, with each metamorphic 
change, the original forces of light and heat by which they 
were produced. This philosopher certainly foreshadows the 
doctrine of half a century later, which we have formularized in 
the term “ correlated ” force. 
The remarkable analogy between this insect light and 
electric light has occurred to many naturalists. The anatomy 
of the electric organs in fishes corresponds in all essential 
points with that of the light-producing organs of insects. A 
congeries of cells, containing semi-fluid albuminous matter, with 
an abundant distribution of nerves and an appreciable meta- 
morphosis of tissue, are characters common to Both. In one 
organ the electric shock especially affects nerve and muscle 
of those who place themselves in contact with it. In the other, 
fight is produced (which is not sensible heat). Both functions 
are periodical, correlative, and exhaustive. 
The inconstancy of result obtained by different experi- 
menters may be in part attributed to the healthy or unhealthy 
condition of the insect and its fight-organ, or to the temporary 
exhaustion of its power. In experimenting on injured and dis- 
eased insects, the writer was struck with the diminished power 
of fight production, and with the doubtful effects of stimuli 
and narcotic agents applied at different times to the same 
insect. The quantity of uric acid crystals found in the atro- 
phied organs of a diseased insect is sometimes remarkable. 
The ventral ganglia may be seen entirely encrusted with uric 
acid, as well as the disorganized muscles and nerves. The 
fight-yielding power, in such cases, fails for days or weeks 
before the insect's death. It may be remarked that the ventral 
ganglia of the female glowworm are much larger than those of 
the larva, and the nerves supplied to the light-organs both 
numerous and of considerable size. It is probable that the expe- 
rimental section of the nerves, and the application of narcotics 
and stimulating agents to the ganglia, would greatly assist in 
determining the exact influence of nerve action on the proper 
function of the fight-organ. 
The effect of magneto- electricity has been variously reported 
by experimenters. Thus Alexander von Humboldt drew a vivid 
fight from a fire-fly that was dying, by touching the ganglia of 
one of its anterior limbs with a piece of zinc and a piece of 
silver. Macaire found luminosity excited by the voltaic pile, 
but not by common electricity. Kolfiker (vide supra) excited 
brilliant fight in Lampyris by applying the induction apparatus. 
Quatrefages and Ehrenberg believe the fight of Noctiluca to 
be an electric phenomenon : and if the evolution of animal 
