1. C. Callan andS. Treiman:Phys. Rev. Lett.,16, 153 (1966).
2. R. Dashen andM. Weinstein:Phys. Rev. Lett.,22, 1337 (1969).
3. X 2 Collaboration:Nuovo Cimento,56 A, 1106 (1968).
4. This suggests that pattern (3) involves a Goldstone mechanism. See ref. (5).
5. S. L. Glashow andS. Weinberg:Phys. Rev. Lett.,20, 224 (1968).