Published online by Cambridge University Press: 14 August 2015
The recent emphasis on stellar evolution, especially as seen in star clusters, has given us — mainly through Sandage's synthesis of the available material — a good outline of the evolutionary process. Although work of a survey nature obviously must be continued, if only to turn up clusters with an age not represented among those now known, I believe the time has come to concentrate a major effort on detailed studies of the brighter known clusters of various ages. Our knowledge of even the Hyades and Pleiades clusters is far from complete. A full account cannot be given here but I would like to mention some examples of the details in the colour-magnitude arrays that may eventually lead to important tests, or revisions, of current evolutionary models.