Then I took the guinea pig from my pocket, held it squirming, and
fastened a little collar about its neck. I unwound a wire from the
plastic disc on the collar so Dr. Whitney could see it. He instantly
recognized the tiny node on the wire as a miniature microphone.
"Remember how you determined that the other pig was asleep?" I asked.
I taped the tiny node to the artery on the pig's neck, carried it
over to the cage, and placed it inside. "I call this my 'Hey, Rube!'"
I explained, grinning. "But imagine it as a little wrist radio
transmitter, worn by everyone who requests them, tuned to the police
broadcast frequency. Radio DF could pinpoint the location in seconds."
Going back to the table, I picked up the pistol. "This one's just for
demonstration," I added, and fired at the cage.
As the guinea pig slumped beside its companion, the disc on its collar
emitted a harsh, buzzing noise.