But Mendel found seven different traits in peas, easy to identify with the naked eye, that occurred in an either-or configuration. They never blended; they were always inherited separately and intact. “Transitional forms were not observed in any experiment,” he said emphatically. In the “height” character, for example, a plant was either very tall—some six feet or more and needing to be staked—or very short, no more than twenty inches high. No traits—at least of the seven Mendel chose—were in between or blended. He called the traits “pairs of differentiating characters.” If he could identify
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