BATS. 33

beetles, the wide mouth and formidable teeth with which
they are provided being an excellent trap for their capture.
Thus they are of great service to vegetation even in our
temperate climate; and in those tropical regions where
insects exist in myriads, many localities would not be habi-
table without this useful family. In this country they
disappear in autumn, and, clustering together in the closest
crannies they can find, remain dormant, until the warm
suns of spring induce them to venture from their retreat.
The female has generally two young ones at a time,
which are naked and helpless at their birth, and constantly
cling to their mother until capable of flight. The ears of
bats are generally very large, so that the sense of hearing
is probably acute. The eyes, on the contrary, are remark-
ably small, and being deeply seated like those of the mole,
they do not seem to be essentially necessary to the animal
in finding its way. The experiments made by Spallanzani
proved that, when blinded, they could find their way be-
tween obstacles of which they had no previous knowledge. —
He suspended willow rods in the room into which he turned
the blind bats, and though he moved these, so as to make
the passages as varied as possible, the animals never struck
one of them, though they flew in all directions. It is
D