“What do you mean?” asked Lew.

“Why, you know that squirrels help to plant the nut trees in a forest.  Some tree seeds, like pine and maple seeds, are so small or light that they are carried easily by birds and winds, and so scattered about.  But acorns and nuts are so heavy that they fall straight down to the earth.  If the squirrels didn’t carry them away and bury them in such quantities, how could we ever have had these great stands of nut and oak trees?”

“I never thought of that,” said Lew.

“It looks as though what Mr. Marlin said was right—­walking about through the forest is only a small part of a forest guard’s work.  He’s got to know an awful lot about things before he can be sure just what he ought to do.”

“I never had any idea how big a job it is, Lew.  And think what a forester must have to know.  I tell you it takes a man to fill a job like that.”

Noon came.  The boys grew hungry.  “I could eat all the sandwiches we have myself,” smiled Charley.  “I wonder if we couldn’t catch some trout to help out.  It would be all right to make a fire over here, I’m sure.  And we’ll keep it so small it won’t make any smoke.  And even if it did, it couldn’t possibly betray the location of our camp.”

They made their way to the stream in the middle of the valley, baited their hooks, and dropped them into the water.  In no time they had half a dozen fine trout.

“You clean ’em, Lew,” suggested Charley, “and I’ll make a little fireplace.”

He selected a little shoulder of earth close to the run and began to dig into it with a stick.  In a moment he had uncovered a deposit of solid clay.  The clay was hard to dig, but he could shape his fireplace in it exactly as he wanted it.  When the task was completed, he started a very small fire with leaves and small branches.  By careful feeding, he kept the flames burning clear, with almost no smoke.  Presently he had a bed of glowing coals that almost filled the little fireplace.

Lew, meantime, had cleaned the fish and cut some black birch branches which he thrust through the fish lengthwise.  Squatting beside the little fire, the two boys now held the fish over the coals, turning them slowly, and roasting them thoroughly.  With the addition of the trout, their meal was ample.

They ate slowly, and after their meal sat for a time beside their fire in the warm sun, watching the forest life about them, and listening to the song of the brook and the myriad other sounds of the woods.  Finally they prepared to leave.  The fire had shrunken to a white bed of ashes.

“We’ll make sure that it is out,” commented Charley.  And he stepped to the run and got a hatful of water, which he poured on the ashes.  To his astonishment the ashes were washed away, leaving the fireplace bare.  The fireplace had changed color and looked as though made of brick.  He touched it and found it as hard as stone.