ell, he's in fine health. And I can't understand why,"
said the physician in a restrained voice.

Pilar tapped one of the report sheets. "You mean the vitamins?"

"I mean the vitamins," said Smathers. "According to Dr. Petrelli, the
fruits contain neither A nor B_1. After living solely on them for four
weeks now, he should be beginning to show some deficiencies--but he's
not.

"No signs?" queried Dr. Pilar. "No symptoms?"

"No signs--at least no abnormal ones. He's not getting enough protein,
but, then, none of us is." He made a bitter face. "But he has plenty of
symptoms."

Dr. Petrelli raised a thin eyebrow. "What's the difference between a
sign and a symptom?"

"A sign," said Smathers testily, "is something that can be objectively
checked by another person than the patient. Lesions, swellings,
inflammations, erratic heartbeat, and so on. A symptom is a subjective
feeling of the patient, like aches, pains, nausea, dizziness, or spots
before the eyes.

"And MacNeil is beginning to get all kinds of symptoms. Trouble is, he's
got a record of hypochondria, and I can't tell which of the symptoms are
psychosomatic and which, if any, might be caused by the fruit."

"The trouble is," said Petrelli, "that we have an unidentifiable disease
caused by an unidentifiable agent which is checked by an unidentifiable
something in MacNeil. And we have neither the time nor the equipment to
find out. This is a job that a fully equipped research lab might take a
couple of years to solve."

"We can keep trying," said Pilar, "and hope we stumble across it by
accident."

[Illustration]

Petrelli nodded and picked up the beaker he'd been heating over an
electric plate. He added a chelating agent which, if there were any
nickel present, would sequester the nickel ions and bring them out of
solution as a brick-red precipitate.

Smathers scowled and bent over his microscope to count more leucocytes.

Pilar pushed his notes aside and went over to check his agar plates in
the constant-temperature box.

The technicians who had been listening to the conversation with ears
wide open went back to their various duties.

And all of them tried in vain to fight down the hunger pangs that were
corroding at their insides.

* * * * *

Broderick MacNeil lay in his bed and felt pleasantly ill. He treasured
each one of his various symptoms; each pain and ache was just right. He
hadn't been so comfortable in