Professor Cox-Raythwaite bent his massive head and shoulders over the little bag and peered narrowly into its obscurity. Then he started. "Good Lord!" he exclaimed. "A glass tumbler! And--is it a sandwich? Why, what on earth----" He made as if to pull the glass out of the bag, and Mr. Tertius hastily seized the great hand in an agony of apprehension. "My dear Cox-Raythwaite!" he said. "Pray don't! Allow me--presently. When either of these objects is touched it must be in the most, quite the most, delicate fashion. Of course, I know you have a fairy-like gentleness of touch--but don't touch these things yet. Let me explain. Shall we--suppose we sit down. Give me--yes--give me one of your cigars." The Professor, plainly mystified, silently pointed to a cigar box which stood on a corner of his desk, and took another look into the bag. "A sandwich--and a glass!" he murmured reflectively. "Um! Well?" he continued, going back to his chair and dropping heavily into it. "And what's it all about, Tertius? Some mystery, eh?" Mr. Tertius drew a whiff or two of fragrant Havana before he replied. Then he too dropped into a chair and pulled it close to his friend's desk. "My dear Professor!" he said, in a low, thrilling voice, suggestive of vast importance, "I don't know whether the secret of one of the most astounding crimes of our day may not lie in that innocent-looking bag--or, rather, in its present contents. Fact! But I'll tell you--you must listen with your usual meticulous care for small details. The truth is--Jacob Herapath has, I am sure, been murdered!" "Murdered!" exclaimed the Professor. "Herapath? Murder--eh? Now then, slow and steady, Tertius--leave out nothing!" "Nothing!" repeated Mr. Tertius solemnly. "Nothing! You shall hear all. And this it is--point by point, from last night until--until the present moment. That is--so far as I know. There may have been developments--somewhere else. But this is what I know." When Mr. Tertius had finished a detailed and thorough-going account of the recent startling discovery and subsequent proceedings, to all of which Professor Cox-Raythwaite listened in profound silence, he rose, and tip-toeing towards the bag, motioned his friend to follow him. "Now, my dear sir," he said, whispering in his excitement as if he feared lest the very retorts and crucibles and pneumatic troughs should hear him, "Now, my dear sir, I wish you to see for yourself. First of all, the glass. I will take it out myself--I know exactly how I put it in. I take it out--thus! I place it on this vacant space--thus. Look for yourself, my dear fellow. What do you see?" The Professor, watching Mr. Tertius's movements with undisguised interest, took off his spectacles, picked up a reading-glass, bent down and carefully examined the tumbler. "Yes," he said, after a while, "yes, Tertius, I certainly see distinct thumb and finger-marks round the upper part of this glass. Oh, yes--no doubt of that!"