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 .