A tube bank apparatus is disclosed for distributing stock in a headbox of a papermaking machine. The apparatus includes a tube having a first and a second portion for the flow therethrough of the stock. The first portion defines a bore for the flow therethrough of the stock, the bore having an upstream and a downstream end. The second portion defines a passage for the flow therethrough of the stock, the passage having an upstream and a downstream extremity. The upstream extremity of the passage cooperates with the downstream end of the bore so that the stock flows from the upstream end to the downstream end of the bore and then through the upstream extremity and then the downstream extremity of the passage. The downstream end of the bore has a cross-sectional area which is less than a further cross-sectional area of the upstream extremity of the passage. Also, the downstream extremity of the passage has a cross-section of trapezoidal configuration.