e.), the admirable
writer of "L'Esprit des betes", speaks of sight and meteorology as the
Carrier-pigeon's guides:

'The French bird,' he says, 'knows by experience that the cold weather
comes from the north, the hot from the south, the dry from the east and
the wet from the west. That is enough meteorological knowledge to tell
him the cardinal points and to direct his flight. The Pigeon taken in
a closed basket from Brussels to Toulouse has certainly no means of
reading the map of the route with his eyes; but no one can prevent him
from feeling, by the warmth of the atmosphere, that he is pursuing the
road to the south. When restored to liberty at Toulouse, he already
knows that the direction which he must follow to regain his Dove-cot
is the direction of the north. Therefore he wings straight in that
direction and does not stop until he nears those latitudes where the
mean temperature is that of the zone which he inhabits. If he does not
find his home at the first onset, it is because he has borne a little
too much to the right or to the left. In any case, it takes him but a
few hours' search in an easterly or westerly direction to correct his
mistake.'

The explanation is a tempting one when the journey is taken north and
south; but it does not apply to a journey east and west, on the same
isothermal line. Besides, it has this defect, that it does not admit of
generalization. One cannot talk of sight and still less of the influence
of a change of climate when a Cat returns home, from one end of a town
to the other, threading his way through a labyrinth of streets and
alleys which he sees for the first time. Nor is it sight that guides my
Mason-bees, especially when they are let loose in the thick of a wood.
Their low flight, eight or nine feet above the ground, does not allow
them to take a panoramic view nor to gather the lie of the land. What
need have they of topography? Their hesitation is short-lived: after
describing a few narrow circles around the experimenter, they start in
the direction of the nest, despite the cover of the forest, despite the
screen of a tall chain of hills which they cross by mounting the
slope at no great height from the ground. Sight enables them to avoid
obstacles, without giving them a general idea of their road. Nor has
meteorology aught to do with the case: the climate has not varied in
those few miles of transit. My Mason-bees have not learnt from any
experience of heat, cold, dry