The Absorption of Bicarbonate Ion by Barley Plants as Indicated by Studies with Radioactive Carbon.

obtained from five rich variable star fields at or near the galactic center. In these regions classical Cepheids with periods of less than ten days are infrequent. Five of the eight of shortest period are bright or highly reddened Cepheids, not near the galactic nucleus but in the neighborhood of the Sun. An examination of the distribution of the periods, magnitudes and longitudes of all the 340 known galactic Cepheids confirms the conclusions based on the study of the five nuclear fields. The correlation of period length with concentration of stellar mass is being further investigated through additional studies of the classical Cepheids in the two Magellanic Clouds.