n the tail-fin of the salmon, the fish having been thrown
over the captor's left arm again, slipped an aluminum button through the
hole, and riveted it securely. The entire process took less than a
minute and a half, and by the time the salmon had been released and
tossed into the water again, Colin was ready with another fish.

"I don't see why the fish don't die as soon as they come out of the
water!" exclaimed Colin.

"For nearly a minute, some fish breathe better out of the water than in
it," the professor answered, "but after that the gills stick together
and the fish strangles. Two or even three minutes will not injure
salmon, and some fish will recover if they are out of water for hours.
Indeed, there are some fish that live out of water most of the time."

"Live out of water?" the boy said in surprise.

"Certainly. Some kinds of fish, at least, can't stay in the water very
long, but remain perched up on the rocks."

"Perching like birds?" Colin said incredulously.

"I know that sounds a little improbable, but it's true, just the same,"
the professor said, smiling. "This is a Fisheries story, not a 'fish
story.' There's a difference. They come from Samoa and belong to the
skippy family. Most of them live on the rocks, and they jump from rock
to rock instead of swimming. Some of them even are vegetarians--which is
rare among fish--and their gills are smaller and stouter. Plenty of them
are only in the water for a little while at high tide, living in the
moist seaweed until the tide rises again."

Colin was silenced, and he went on vigorously dipping up salmon.

"How many fish are you going to tag?" the boy asked, when a couple of
hours had passed by.

"Sixty," the professor answered, "and we must be nearly through, for I
have only a few buttons left."

Secretly the boy was much relieved, for his back was tired from stooping
and netting heavy fish for two hours, but he would have worked to utter
exhaustion rather than complain. However, within another quarter of an
hour, the last fish was dropped over the side and the party was on its
return journey.

"Why don't you stop and see the hatchery?" suggested the professor, in
return to a host of questions put to him by the boy concerning salmon
culture.

"I'd like to, ever so much, if I might," was the answer, and Colin
looked up at the foreman.

"Come right along," was the latter's immediate response. "It isn't much
of a place to look at, but you can se