terly disgusting odor. Locked up, Calhoun could not smell it.
But Murgatroyd could. He sniffed. He said impatiently to Calhoun:

"_Chee! Chee-chee!_"

Calhoun stared. His lips tightened. It was the function of the
_tormal_ members of the Med Service to react to any infection more
swiftly than humans could do, and to develop antibodies which
destroyed that infection and could be synthesized to cure it in
humans. But Murgatroyd was immune only to infections. To toxins. He
was not immune to an appetite-causing molecule demanding more of
itself on penalty of madness. Murgatroyd had no more inherent
resistance than a man.

"_Chee-chee!_" he chattered urgently. "_Chee-chee-chee!_"

"It's got him," said Calhoun. He felt sickened. "It'll have me.
Because I can't synthesize anything as complex as the computer says is
needed to control the molecular population that makes paras!"

Murgatroyd chattered again. He was indignant. He wanted something and
Calhoun didn't give it to him. He could not understand so preposterous
a happening. He reached up and tugged at Calhoun's trouser-leg.
Calhoun picked him up and tossed him the width of the control room.
He'd done it often, in play, but this was somehow different.
Murgatroyd stared incredulously at Calhoun.

"To break it down," said Calhoun bitterly, "I need aromatic olefines
and some acetone, and acetic-acid radicals and methyl submolecular
groups. To destroy it absolutely I need available unsaturated
hydrocarbons--they'll be gases! And it has to be kept from reforming
as it's broken up, and I may need twenty different organic radicals
available at the same time! It's a month's work for a dozen competent
men just to find out how to make it, and I'd have to make it in
quantity for millions of people and persuade them of its necessity
against all the authority of the government and the hatred of the
paras, and then distribute it--"

* * * * *

[Illustration]

Murgatroyd was upset. He wanted something that Calhoun wouldn't give
him. Calhoun had shown impatience--almost an unheard-of thing!
Murgatroyd squirmed unhappily. He still wanted the thing in the chest.
But if he did something ingratiating....

He saw the blaster, lying on the floor. Calhoun often petted him when,
imitating, he picked up something that had been dropped. Murgatroyd
went over to the blaster. He looked back at Calhoun. Calhoun paced
irritably up and down. The grid operator st