I want to state a few questions which are raised by the observations of stellar Li and Be, and to see how far we can go in giving answers.

I do not believe that we can, at the present time, give very definite answers to most of these questions and build up a unique model in which all observations are properly understood. We are still faced with different possibilities which can not be excluded, but can only be classified according to their degree of ‘plausibility’. Although we are led to choose one of these possibilities in the light of present data, it seems wise to keep the other possibilities in the back of our mind, and to assess their merit. Considering this, a few alternate models will be described and discussed.