“It’s this,” said Frank.  “I’ve seen a good many alligators in the river lately, and I’ve had my eye on one big old fellow in particular.  He spends most of his time in that little cove down there; but I’ve noticed that whenever a dog barks, close to the river or when he is crossing on the ferry, the old ’gator paddles out a little way from the cove, and looks very wishfully in that direction.  I know alligators are more fond of dog-meat than anything else, but they won’t refuse fish when nothing better offers.  Now look here.”

Going to the other end of the boat as he spoke, Frank produced a coil of light, but strong Manila line that he had obtained at the house.  To one end of this rope were knotted a dozen strands of stout fish-line, and the ends of these were made fast to the middle of a round hickory stick, about six inches long, and sharply pointed at each end.  These sharp ends had also been charred to harden them.

“There,” said Frank, as Mark gazed at this outfit with a perplexed look, “that’s my alligator line; and after dinner, if you’ll help me, we’ll fish for that old fellow in the cove.”

“All right,” said Mark; “I’m your man; but where’s your hook?”

“This,” answered Frank, holding up the bit of sharpened stick.  “It’s all the hook I want, and I’ll show you how to use it when we get ready.”

After dinner the boys found several teams on both sides of the river waiting to be ferried across; then Mark had to go with Jan for a load of fence posts, so that it wanted only about an hour of sundown when they finally found themselves at liberty to carry out their designs against the alligator.

Frank said this was all the better, as alligators fed at night, and the nearer dark it was, the hungrier the old fellow would be.

Taking a large fish, one of a half a dozen he had caught during the day, Frank thrust the bit of stick, with the line attached, into its mouth and deep into its body.  “There,” said he, “now you see that if the ’gator swallows that fish he swallows the stick too.  He swallows it lengthwise, but a strain on the line fixes it crosswise, and it won’t come out unless Mr.  ’Gator comes with it.  Sabe?”

“I see,” answered Mark; “but what am I to do?”

“I want you to lie down flat in the boat, and hold on to the line about twenty feet from this end, which I am going to make fast to the ferry post.  Keep it clear of the bank, and let the bait float well out in the stream.  The minute the ’gator swallows it, do you give the line a jerk as hard as you can, so as to fix the stick crosswise in his gullet.”

“All right,” said Mark; “I understand.  And what are you going to do?”

“Oh, I’m going to play dog,” answered Frank, with a laugh, as he walked off down the riverbank, leaving Mark to wonder what he meant.

Frank crept softly along until he was very near the alligator cove, just above which he could see the fish, which Mark had let drop down-stream, floating on the surface of the water.  Then he lay down, and began to whine like a puppy in distress.  As soon as Mark heard this he knew what his friend meant by playing dog, and he smiled at the capital imitation, which would have certainly deceived even him if he had not known who the puppy really was.