Reflections on the origin of optical asymmetry on earth.

The importance of optical purity, which was stressed in an earlier review, is reassessed in the light of recent evidence concerning the optical configuration of amino acids in biological systems. The most significant fact to emerge in recent years that bear on the origin of optical asymmetry is the experimental evidence for the Salam-Weinberg theory. However, the problem remains: is the effect of PNC-interactions too small to be detectable, and if it is so small, can it be of any significance? In view of the contradictory and confusing nature of the evidence on the induction of optical activity, it is suggested that the Bremen Symposium should agree on some experimental protocols.