cause
a slight shock, if loud enough, but not a perceptible vibration May not
this vibration--felt as in a cathedral we feel the vibrations of the
organ-pipes in the bones of the chest and head or on the covers of the
hymn-book in our hands--serve to keep the insects together, and enable
the females to keep within sight of the males? The sight of an insect is
in one sense poor--it consists of a kind of mosaic picture, and for one
insect to distinguish another clearly the distance between them must not
be very great. Certain gregarious birds and fish whose colouring is
protective have a habit of showing their white bellies as they swerve on
changing their direction. These signals help to keep the flock together.
The white scut of the rabbit and of certain deer is a signal for other
deer or rabbits to follow a frightened flock. It is obviously to the
advantage of the Cigale to follow a gregarious habit, if only for
purposes of propagation, for this would be facilitated by the sexes
keeping together, and, deaf or otherwise, the vibrations of its cry
would enable it to do so. It would be easy to show _a priori_ that the
perception of such vibrations must cause the insect pleasure, as they
stimulate a nervous structure attuned to the perception or capable of
the production of certain complex vibrations. The discord of the cry is
caused by the fact that it consists of a number of vibrations of
different pitch. Some would set the contents of the male resonating
cavities in vibration; others would affect the less regular cavities in
the thorax of the female. We might compare the Cigale's cry to a
sheep-bell. That it is felt and not heard explains its loudness and its
grating quality. A Cigale with the resonating cavities destroyed would
possibly be lost. The experiment is worth trying.--[TRANS.]]

[Footnote 2: It is not easy to understand why the Mantis should paralyse
the cricket with terror while the latter will immediately escape when
threatened by other enemies. As many species of Mantis exactly mimic
sticks and leaves when motionless for purposes of defence, is it not
possible that they mimic their surroundings for purposes of offence as
well? It is easy and natural to say that the Mantis presents a
terrifying aspect. It does to us, by association; but how can we say
that it represents anything of the sort to the probably hypnotic or
automatic consciousness of the cricket? What does it really represent,
as seen from below