Although the cause of the split limbs, extra legs, missing eyes and other frog deformities reported from Minnesota and many other states is still unknown, evidence linking deformed frogs and farm chemicals continues to mount. Researchers will discuss those findings and others in San Diego this week at a conference sponsored by the National Science Foundation. Minnesota Public Radio's Mary Losure reports. When researcher Martin Ouellet first began finding deformed frogs along the St. Lawrence River in Quebec in 1992, he suspected a link betw