d
plant is truly a vegetable wonder. At one moment a bed of soft and
vivid green, the next a touch from a finger and, in the twinkling of
an eye, it has changed into an unsightly tangle of seemingly dead and
withered stems. In this case death-feigning seems absolutely
successful as far as protection is concerned; for surely no
grass-eating animal would touch this withered stuff, especially if
there were other greens in the neighborhood. Death-feigning in plants,
and kindred phenomena, are not due, however, to conscious
determination; they are, in all probability, simply the result of
reflex action.

[A] Darwin, _Insectivorous Plants_, Chap. V. _et seq._

[B] Darwin, _Power of Movement in Plants_, pp. 107-109.

Recently, I saw this stratagem perpetrated by a creature so low in the
scale of animal life, and living amid surroundings so free from ordinary
dangers, that, at first, I was loath to credit the evidence of my own
perceptive powers; and it was only after long-continued observation that
I was finally convinced that it was really an instance of
letisimulation.

The animal in question was the itch mite (_Sarcoptes hominis_), which is
frequently met with by physicians in practice, but which is rarely seen,
although it is very often felt, by mankind, especially by those
unfortunates who are forced by circumstances to dwell amid squalid and
filthy surroundings. _Sarcoptes hominis_ is eminently a creature of
filth, and is primarily a scavenger living on the dead and cast-off
products of the skin. It is only when the desire for perpetuating its
race seizes it that it burrows into the skin, thereby producing the
intolerable itching which has given to it its very appropriate name. It
is only the females that make tunnels in the skin; the males move freely
over the surface of the epidermis. The females make tunnels or
_cuniculi_ in the cuticle, in which they lay their eggs, and they can
readily be removed from these burrows with a needle. While observing one
of these minute _acarii_ through a pocket lens, as it crawled slowly on
the surface of the skin, I wished to examine the under surface of its
body. When I touched it with the point of a needle in attempting to
turn it upon its back, it at once ceased to crawl and drew in its short,
turtle-like legs toward its sides. It remained absolutely without motion
for several seconds, and then slowly resumed its march. Again I touched
it, and again