The membranous cymbal and the steel cricket are analogous instruments.
Both produce a sound by reason of the rapid deformation and recovery of
an elastic substance--in one case a convex membrane; in the other a slip
of steel. The "cricket" was bent out of shape by the thumb. How is the
convexity of the cymbals altered? Let us return to the "church" and
break down the yellow curtain which closes the front of each chapel. Two
thick muscular pillars are visible, of a pale orange colour; they join
at an angle, forming a ~V~, of which the point lies on the median line
of the insect, against the lower face of the thorax. Each of these
pillars of flesh terminates suddenly at its upper extremity, as though
cut short, and from the truncated portion rises a short, slender tendon,
which is attached laterally to the corresponding cymbal.
There is the whole mechanism, no less simple than that of the steel
"cricket." The two muscular columns contract and relax, shorten and
lengthen. By means of its terminal thread each sounds its cymbal, by
depressing it and immediately releasing it, when its own elasticity
makes it spring back into shape. These two vibrating scales are the
source of the Cigale's cry.
Do you wish to convince yourself of the efficiency of this mechanism?
Take a Cigale but newly dead and make it sing. Nothing is simpler. Seize
one of these muscular columns with the forceps and pull it in a series
of careful jerks. The extinct _cri-cri_ comes to life again; at each
jerk there is a clash of the cymbal. The sound is feeble, to be sure,
deprived of the amplitude which the living performer is able to give it
by means of his resonating chambers; none the less, the fundamental
element of the song is produced by this anatomist's trick.
Would you, on the other hand, silence a living Cigale?--that obstinate
melomaniac, who, seized in the fingers, deplores his misfortune as
loquaciously as ever he sang the joys of freedom in his tree? It is
useless to violate his chapels, to break his mirrors; the atrocious
mutilation would not quiet him. But introduce a needle by the lateral
aperture which we have named the "window" and prick the cymbal at the
bottom of the sound-box. A little touch and the perforated cymbal is
silent. A similar operation on the other side of the insect and the
insect is dumb, though otherwise as vigorous as before and without any
perceptible wound. Any one not in the secret would be amazed at the
result of my pin-prick, when the destruction of the mirrors and the
other dependencies of the "church" do not cause silence. A tiny
perforation of no importance to the insect is more effectual than
evisceration.
Public-domain text, read in full here on John Shaqi.
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