But at the dinner which was brought to them in the middle of the day Ned showed a marked failure of appetite, and Mr. Austin felt real concern.  The boy, however, was sure that he would be all right before the day was over.

“It must be the lack of fresh air and exercise,” said Mr. Austin.  “You can really take exercise in here, Ned.  Besides, you said that you were going to escape.  If you fall ill you will have no chance at all.”

He spoke half in jest, but Ned took him seriously.

“I am not ill, Uncle Steve,” he said.  “I really feel very well, but I have lost my appetite.  Maybe I am getting tired of these Mexican dishes.”

“Take exercise! take exercise!” said Mr. Austin with emphasis.

“I think I will,” said Ned.

Physical exercise, after all, fitted in with his ideas, and that afternoon he worked hard at all the gymnastic feats possible within the three rooms to which they were confined.  De Zavala came in and expressed his astonishment at the athletic feats, which Ned continued with unabated zeal despite his presence.

“Why do you do these things?” he asked in wonder.

“To keep myself strong and healthy.  I ought to have begun them sooner.  The Mexican air is depressing, and I find that I am losing my appetite.”

De Zavala’s eyes opened wide while Ned deftly turned a handspring.  Then the young American sat down panting, his face flushed with as healthy a color as one could find anywhere.

“You’ll have an appetite to-night,” said Mr. Austin.  But to his great amazement Ned again played with his food, eating only half the usual amount.

“You’re surely ill,” said Mr. Austin.  “I’ve no doubt de Zavala would allow us to have a physician, and I shall ask him for one.”

“Don’t do it, Uncle Steve,” begged Ned.  “There’s nothing at all the matter with me, and anyhow I wouldn’t want a Mexican doctor fussing over me.  I’ve probably been eating too much.”

Mr. Austin was forced to accede.  The boy certainly did not look ill, and his appetite was bound to become normal again in a few days.  But it did not.  As far as Mr. Austin could measure it, Ned was eating less and less.  It was obvious that he was thinner.  He was also growing much paler, except for a red flush on the cheek bones.  Mr. Austin became alarmed, but Ned obstinately refused any help, always asserting with emphasis that he had no ailment of any kind.  But the man could see that he had become much lighter, and he wondered at the boy’s physical failure.  De Zavala, also, expressed his sorrow in sonorous Spanish, but Ned, while thanking them, steadily disclaimed any need of sympathy.

The boy found the days hard, but the nights were harder.  For the first time in his life he could not sleep well.  He would lie for hours so wide awake that his eyes grew used to the dark, and he could see everything in his room.  He was troubled, too, by bad dreams and in many of these dreams he was a living skeleton, wandering about and condemned to live forever without food.  More than once he bitterly regretted the resolution he had taken, but having taken it, he would never alter it.  His silent, concentrated nature would not let him.  Yet he endured undoubted torture day by day.  Torture was the only name for it.