You may count these caddis baits
by hundreds of thousands; whether the trout eat them case and all, is
a question in these streams. In some rivers the trout do so; and
what is curious, during the spring, have a regular gizzard, a
temporary thickening of the coats of the stomach, to enable them to
grind the pebbly cases of the caddises. See! here is one whose house
is closed at both ends--'grille,' as Pictet calls it, in his
unrivalled monograph of the Genevese Phryganeae, on which he spent
four years of untiring labour. The grub has stopped the mouth of his
case by an open network of silk, defended by small pebbles, through
which the water may pass freely, while he changes into his nymph
state. Open the case; you find within not a grub, but a strange
bird-beaked creature, with long legs and horns laid flat by its
sides, and miniature wings on its back. Observe that the sides of
the tail, and one pair of legs, are fringed with dark hairs. After a
fortnight's rest in this prison this 'nymph' will gnaw her way out
and swim through the water on her back, by means of that fringed tail
and paddles, till she reaches the bank and the upper air.
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