During this part of the Symposium, so carefully prepared by Messrs. Denisse and Pawsey, a great amount of new data has been presented, almost all obtained since the last international meeting on these subjects only one year ago. It is clear that this is a part of astronomy that develops impetuously. Hypothetical theories have been definitely confirmed by direct observation; on the other hand, new facts have been disclosed, increasing the complication of the phenomena; but we have reason to hope that we are in a transitory stage and that the complications will gradually be explained on clear and simple principles. It is of course impossible to mention in this summary the contents of all communications; only the more essential results will be reviewed.