Tube for yarn bobbins

A plastic tube for retaining yarn wound thereon while being subjected to a liquid treatment in an apparatus in which a plurality of tubes are placed end-to-end on a perforated distributor pipe and in which treatment liquid is pumped through the wound yarn, said tube having a narrow end and a broad end and a conically-shaped yarn-carrying surface extending between said ends, said narrow end having an outside diameter less than the inside diameter of said broad end whereby said narrow end can fit into the broad end of an adjacent end of a tube of the same construction so that compression of the wound yarn and of the tube can be effected, said tube having a V-shaped slit extending longitudinally along a major part of the length of said tube, said slit having a pointed end spaced from the broad end of said tube and a wide end open through the narrow end of said tube, said slit permitting radial compression of that longitudinal portion of said tube between the pointed end of the slit and the narrow end of the tube upon compression of yarn wound on said tube so that the conicity of said tube increases concurrently with compression.