US Patent 4,759,379 assigned to Koerber AG. A laser or a spark discharge apparatus which is used to perforate the wrapping material for rod-like fillers of tobacco and/or filter material is adjusted in dependency on variations of the characteristics of signals which denote the mass per unit length of a trimmed filler having a predetermined hardness. The wrapping material is tipping paper or cigarette paper and can be perforated prior or subsequent to draping around the trimmed filler, and the draped filler is thereupon subdivided into sections of desired length. Signals denoting the mass per unit length of the filler can be influenced by signals denoting the hardness of the filler, the filling power of the filler, the temperature of fibrous material of the filler, the moisture content of fibrous material of the filler and/or other parameters of the fibrous material and/or filler.