Abstract: A stirring mechanism, with a plurality of hollow, at least partially conically shaped stirring elements, which are provided with two openings, are symmetrically offset and are fixed on the stirring shaft (2) at least approximately tangential to an imaginary circular cylinder coaxial to the stirring shaft.In the starting phase, the stirred substance flows laminarly through the stirring elements 8. However, as soon as they have reached a predetermined minimum velocity of about 1.3 m/s, the flow inside the stirring elements 8 is forced to reverse by dynamic pressure. The resultant counterflow (11, 12, 13) brings about an outstanding, extensive and nevertheless extremely gentle stirring effect with low power consumption. Also, an effective and uniform gassing can be obtained with simple means, without the stirring velocity having to be increased.