s without incident, and he arrived in Astoria in time to
proceed the same afternoon to the cottage of the professor, where he was
to stay that night, having found a letter of welcome awaiting him in
Astoria.

Reaching the house he presented his letter of introduction, and was
cordially greeted. Finding that the boy was really interested, his host
took him to a tiny laboratory of his own, where he was experimenting on
the various diseases of the salmon and the trout.

This gave Colin an entirely new outlook on the Fisheries' activities.

"I never thought of fishes being sick before!" he exclaimed. "Are there
fish-doctors in the Bureau?"

"There's a large division of the service given to that very work," the
professor replied, "only there are so many millions of fish that we do
not try to cure the individual, but only endeavor to prevent the
disease. You know what the work of a veterinary is?"

"Of course," the boy responded.

"And you know that the United States Government has an inspector at
every place where cattle and sheep and pigs are slaughtered to see that
no diseased animals are sold?"

"Yes," the boy answered, "I have heard of that, too."

"Since there is almost as much fish eaten in this country as there is
meat," the professor continued, "Uncle Sam sees to it that no diseased
fish are sold for food."

"I don't quite see how," the boy responded; "there can't be an inspector
at every place where they catch fish."

"Certainly not, but as long as there is no disease among fish, there can
be no diseased fish. We try to prevent the diseases. Now here, for
example," he continued, "are a lot of fish that have a kind of malign
growth. It comes very frequently among the trout and salmon that are
artificially raised, and sometimes we find it among fish that have been
reared in a state of nature, and I have been working for some time on
this and I hope this year--or at all events by next season--to be able
to show the cause of the disease. That is really my problem, Colin, but
the details of it are too complicated to explain easily. But you have
come at a particularly good time," he continued, "because I have been
wanting to do an experiment which I thought might interest you, and I
waited until you came. If you like, we'll go out to-morrow."

"I should, ever so much," Colin exclaimed. "What's the experiment?"

"When the salmon come in from the sea," the professor began, "there is a
great deal of hesitation