"Had him out this morning?" "Grody took him to the shoer, that's all." "What did he say?" "Said there was nothing the matter with the way Nemo is shod." "Perhaps he lied. Didn't want to hurt his business. Did he do anything?" "Yes, he reset the shoe on the lame foot." "Hum! Horse may be all right by to-morrow or next day." "I do not think he will, doctor." "Eh? Why not?" "Because I have reasons to believe he was made to go lame." "Is that so? Well, now the matter becomes more interesting. What causes you to think anything of the sort?" Frank explained, and the doctor listened attentively to his story. "This is worth investigating," he declared. "I know a few of the tricks of these fellows, and I think I'll find out what was done to your horse, if anything was done." The boys watched the doctor with great interest. They saw him examine the lame leg from the knee down. In doing this he put on a pair of spectacles. Nemo was nervous. He seemed afraid the doctor would hurt him, and it was not found easy to make him stand. At last Dr. Cobb uttered a sharp exclamation. "Bring my case, which you will find under the seat in my carriage, Grody," he directed. Grody hastened to obey. "Have you found out what the matter is, doctor?" Frank anxiously asked. "I believe so, but I am not sure yet." Jack and Harry came near, eager to learn what had been done to lame the horse. The doctor opened his case, and took out some tweezers. "Do you see this hair here?" he asked, having brushed the fetlock aside and taken the end of a hair in his fingers. The boys saw it, but wondered what that hair could have to do with the lameness of the horse. "It is not the right color," declared the doctor. "You see it is white, instead of being the color of the other hairs here." Despite himself Frank felt his anger rising. How could the color of a hair make the horse lame? Did the man take him for a fool because he was a boy? The three boys exchanged glances, and Harry made a threatening gesture at the back of the doctor's head. "I see the hair is white, sir," said Frank, his voice cold and hard; "but I scarcely think a white hair could make my horse go lame. I know I am a boy, but I do not like to be taken for a fool." The doctor looked up and saw the indignation expressed on the faces of the three lads. Then he chuckled in a singular way and said: "Wait till I get through, young man. I do not take you for a fool ordinarily, but you can easily make a fool of yourself over this matter." He had taken the short white hair, which was very coarse, in his fingers, having separated it from the others. "Notice the peculiar place where this hair seems to grow," he directed. "It is not a part of the fetlock, but the fetlock hid it from view. I am going to pull this hair out, but first I want you to notice that there is another hair, it seems, on the other side of the ankle, and it is just like this. See it?" The boys saw it.