“There is just one more test,” he muttered. “Although I believe it is superfluous. However, here goes.” He put the tuft of grass to his tongue. “I knew it,” was his soft exclamation. “Salt! It could not be anything else.” He pressed a push button at the side of his table, and then unfastened the door of the room. As he returned to his seat, he puffed contentedly at his cigar, still regarding the mud and tuft of grass on the white paper. “Want me, chief?” A young fellow, with the bright, alert expression on his rather thin features that tells of an active brain, stood in the doorway. “Yes, Patsy! Close the door and come over here.” The young man obeyed, and Nick Carter pointed to the stuff on the paper on his table. “What’s that, Patsy?” Patsy Garvan--for it was the trusted young assistant of that name who had come in--bent closely over the paper and studied the grass for a moment. “I should say it is salt meadow grass,” he answered. “Why do you think so?” “It is coarse, and there is a color to it you don’t see in any other kind. If you’ll let me taste it, I can tell you.” Nick Carter laughed and drew several whiffs of smoke from his cigar before he spoke again. “That’s just what I did, Patsy,” he said, at last. “Put your tongue to it and let me know what you think.” Patsy lifted the paper and put out his tongue. “I should say so,” was his remark, as he replaced the paper and its contents on the table. “Gee! You couldn’t fool me on that. Where did you get it?” “Never mind about that, Patsy. Where do you suppose this grass and mud came from?” “Hackensack meadows, of course! Have you been over there?” “No. But the man from whose shoe this came must have been. Look here Patsy! Chick has been taken away against his will----” “What?” blurted out Patsy Garvan. “Chick? Say! Let me----” “And one of the men who took him dropped this mud and grass from his shoe.” “He did? Say, chief! We’re going after Chick right away, ain’t we?” Patsy was on his feet, his fists clenched, and anger blazing all over his face. He had a regard for Chick only second to that he felt for Nick Carter himself. The thought of his chum being held anywhere made him frantic. “Keep cool, Patsy! We’ll go, of course! But we’ll have to be careful.” “How do you mean careful?” “This is the open season for duck hunting, and there are any number of ducks over there, in the meadows.” “Sure! But I don’t quite get you? What do I care for the darned ducks?” “Put on that leather coat you have,” directed Nick calmly. “And your high boots, as well as your big corduroy cap. Get your double-barreled gun and that string of wooden decoy ducks we used down on the Chesapeake two years ago. You have them, haven’t you?” “Yes.” “Very well. Don’t be more than ten minutes. Then come down to the library again. I’m going to put on my duck-hunting rig, too.” CHAPTER IV. THE ICE HOUSE IN THE SWAMP.