The Commission has found no opportunity of acting collectively in the last triennial period. Progress in the theoretical study of the constitution of the stars must be mainly a matter of individual effort; and it would be impracticable and undesirable to seek uniformity of views and methods.

A brief reference may here be made to some of the problems now especially engaging attention. In this connection I would call attention to a valuable Report on “Die Theorie des Sterninnern und die Entwicklung der Sterne” (Ergebnisse der exakten Naturwissenschaften, Bd. XVI, 1937) by a member of the Commission, B. Strömgren, which deals especially with progress in the last ten years, and shows very clearly the present state of the subject.