126 
VERTEBRATA. 
BATS IN A CAVERN. 
to very many other animals. A horse, in the dark, pauses when he comes to a closed gate, 
though he never was on the road before. Nocturnal beasts do not more frequently fall into pits 
and over precipices than beasts which are abroad during the day, and have their eyes to guide 
them ; and nocturnal birds do not fly against trees any more than daylight birds. People, too, 
will keep a well-known path, though the night be pitch dark. The explanation of these cases 
has been sought in the supposition of a sixth sense, but as yet no satisfactory solution of such 
phenomena has been found. 
The breeding of bats takes place at the very hottest time of the year. The young, which are 
usually two in number, are naked and helpless at their birth — capable only of clinging to the teats 
of their mother, which, however, they do with the greatest firmness and pertinacity. This habit 
to them is necessary, for the mother does not lie down, or even stand on the ground, when she 
suckles her young, as is the case with most of the mammalia. She hangs suspended by the nails 
of her thumbs, or more generally by those of her hind feet, to the branch of a tree, or some cranny 
or irremilaritv in a ruin or cavern. There is no nest in Avhich she can leave the vonno- ones when 
she goes out to feed, and thus she must bear them about attached to her body till they are capa- 
ble of flight. The female has no mai'supium ; but this habit resembles somewhat that of the mar- 
supial animals. The young are very immature when produced, and their nest and place of safety 
and repose is the bod}^ of their mother. 
Some of the species occasionally fly during the day, but this practice is by no means common, 
and is confined to some of the foreign species, which are in part vegetable-feeders. In teinpcrate 
climates, they conceal themselves during the day, even in the season of their greatest activity. 
Caverns, holes of trees, and walls and ruined buildings, are their retreats, and from these they 
issue forth as dusk begins to set in, flutter about in their laborious flight, and capture such insects 
as are then on the wing — gnats, rausquitos, moths, and beetles, — their wide gape, with its formida- 
ble teeth, being an excellent trap for the capture of such prey. 
The service which they render to vegetation by the destruction of insects, w^hich in the larva 
state prey upon it, is very considerable, even in temperate climates. Some of the hot countries, 
in which these swarm by myriads, could not, but for them, be inhabited. In humid places, on the 
margins of tropical forests, musquitos are troublesome enough as it is, but if the bats did not 
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