Galaxies that feed on gas.

Research concerning cooling flows is reviewed. The discovery of cooling flows streaming in towards NGC 1275, the central galaxy in a cluster in the constellation Perseus, is discussed. It is suggested that cooling gas flows into quasars at a rate of 100 to 200 solar masses/year and into Cygnus A, a powerful radio galaxy, at a rate of 250 solar masses/year. The role of black holes in providing the power of active galaxies is considered. The possible role of space telescopes and X-ray satellites in future studies of cooling flows is examined.