A cause of deformity is known in at least one situation. Trematodes, a parasitic flatworm, are responsible for the high frequency of missing and extra limbs in certain frogs and salamanders in northern California, according to Stanley K. Sessions of Harwick College, Oneonta, N.Y. He found that 72 percent of 280 tadpoles and young froglets had a wide range of limb deformities and that 40 percent of a sample of more than 4,000 larval and newly metamorphosed salamanders were affected too.
These and other studies are being discussed over several months by scientists in a
worldwide conference on World Wide Web.