Marable shrugged. His examination was interrupted by the arrival of the museum's chemist, sent for by Young. The chemist took a sample of the black liquid for analysis. Reports were coming in from all over the museum, different departments declaring, one after another, that nothing had been disturbed or stolen from their sections. Betty Young went again to Marable's side. She followed the direction of his eyes, and saw long, clawlike marks on the floor, radiating from the sepia. "Doctor Marable," she said, "please don't--don't look any longer. Leave this terrible place for the day, anyway, until we see what happens in the next twenty-four hours." He smiled and shook his head. "I must make a search," he replied. "My brain calls me a fool, but just the same, I'm worried." "Do you really think ...?" He nodded, divining her thought. The girl shivered. She felt terror mounting to her heart, and the matter-of-fact attitudes of the others in the great laboratory did not allay her fears. Rooney's body was removed. The place was cleaned up by workmen, and Marable's search--if that was what his constant roving about the laboratory could be called--ceased for a time. The chemist's report came in. The black liquid was some sort of animal secretion, melonotic probably. * * * * * In spite of the fact that they had learned so many facts about the murder, they as yet had not solved the mystery. Who had murdered Rooney, and why? And where had his blood gone to? In no other rooms could be found any traces of a struggle. "If you won't do anything else, please carry a gun," begged Betty of Marable. "I'm going to try to take father home, right after lunch, if he'll go. He's so stubborn. I can't make him take care. I've got to watch him and stay beside him." "Very well," replied Marable. "I'll get a revolver. Not that I think it would be of much use, if I did find--" He broke off, and shrugged his broad shoulders. Leffler came storming into the room. "What's this I hear?" he cried, approaching Marable. "A watchman killed in the night? Carelessness, man, carelessness! The authorities here are absurd! They hold priceless treasures and allow thieves to enter and wreak their will. You, Marable, what's all this mean?" Leffler was angry. Marable looked into his red face coolly. "We do the best we can, Mr. Leffler," he said. "It is unlikely that anyone would wish to steal such a thing as that block of amber." He waved toward the giant mass. Leffler made a gesture of impatience. "It cost me many thousands of dollars," he cried. "It is time for lunch, Professor," said Betty. Marable bowed to Leffler and left the millionaire sputtering away, inspecting the various specimens he had contributed. The one o'clock gong had struck, and all the workers and investigators were leaving in paleontological laboratories for a bite to eat. * * * * *