"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.