ng, though too tired to dream of it
at night. Nor did he forget his swimming, and at the beach in Buzzards
Bay he swam a mile or so each day, the admiration and the envy of all
the M. B. L. students. But Colin speedily won their friendship, for he
never hesitated to help other swimmers in every way he could, even
teaching little tricks of style that were all his own and which had gone
far to win him his championship.

As Director Prelatt had promised, Colin was given an opportunity to keep
some research work in hand, although he found--as had been
foretold--that he had but little time for it. The director was engaged
upon a most interesting and important investigation, which, like all
those that were in progress at the laboratory, had a strong economic
value. This was the study of the life history of the whelk.

"At first sight," the director said to him, when explaining the problem,
"it does not seem as though the biology of a sea-snail were a matter of
much importance to the country, but as a matter of fact, to a great
extent the oyster industry--which reaches millions of dollars annually
and gives employment as well as food to thousands of people--depends
upon that very thing."

"Just how, Mr. Prelatt?" inquired Colin.

"All creatures have their own special enemies," the director answered;
"and everything is so equally balanced that there are enough oysters
born to keep up the supply in spite of the attacks of the whelk, or
oyster-drill as it is termed. When man comes on the scene, however, and
commences to dredge the oysters, the combination of the market and the
drill together is too much for the oyster-beds and they soon become
depleted."

"That's the way it is with fish, too!"

"With everything," was the assenting answer. "Now there are two ways to
overcome this condition. One is the way in which we handle the same
question with fish--by artificially hatching millions more eggs every
year than would have been hatched during a state of nature. The other is
by attacking the enemy of the oyster and thus enlarging the chances of
those that hatch naturally. The latter we can't do with fish."

"Why not, sir?"

"Because the enemies of fish are numerous and free-swimming," was the
answer, "and also because fish produce an enormous amount of eggs.
Oysters do also, but fertilization is so largely a matter of chance that
but a few of the tens of thousands of eggs ever really have a chance to
become young oysters.