Medicine: Alimentary FM

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Walkie-talkies had not been invented in 1910, when Humorist Robert Benchley delivered his uproariously unmedical lecture, "Through the Alimentary Canal with Gun and Camera," so the imaginary expedition from gullet to fundament could make no on-the-spot broadcasts of its progress. Last week Manhattan's Rockefeller Institute for Medical Research announced the development of a tiny capsule FM transmitter that can make just such broadcasts. It is small enough (|⅛in. long, 4/10 in. in diameter) to be swallowed like an oversized pill. Conceived by New York Physician John T. Farrar, the plastic-encased transmitter was designed by RCA's doughty old (67) Electronics Pioneer Vladimir Kosma Zworykin (who perfected the electron microscope) to record changes in activity in the digestive tract.

Weak signals (measured in microwatts) from the radio pill's transistor oscillator can be received a few feet away, vary in frequency with changes of pressure on a rubber membrane stretched across one end (e.g., frequency decreases when the pill reaches a churning stomach, rises when it enters a slowly pulsating small intestine). A fluoroscope can keep track of the pill's position in the body, while a receiver picks up the FM signals, presents them to the examiner on an oscilloscope as graph waves. Prospects are good that the transmitter will replace awkward, uncomfortable tubes now used to supplement X-ray examination. The pill broadcaster may help spy out certain hard-to-diagnose ailments, e.g., colitis (inflammation of the large intestine).

Refinements still to be made by Zworykin's technicians include modifying the capsule so that it can transmit information on internal temperatures and acidity, and reducing its size. One refinement ruled out (partly because of bad lighting conditions ) by the inventor of edible FM: intestinal television.