Abstract: A continuous web in the form of a hose-like thermoplastic foil is intermittently fed through a welding and severing station in which two transverse weld seams on the foil are made and simultaneously a cutting blade severs a completed bag along a line between the weld seams. A transfer unit arranged immediately below the welding station temporarily seizes the severed bag, displaces the same a small distance in feeding direction, and then dashes the rear portion with the still plastic weld seam against an alignment line of a stacking station. The stacking station is arranged a small distance below the welding station at the other side of the severed bag, and the still plastic weld seam fuses with the corresponding weld seam of the preceding bag interlocked in the stack. The completed stack is discharged in a perforating station where the tearing line is perforated simultaneously through all stacked bags. If desired, additional holes are punched between the upper edge of the bag and the perforation line.