A distributor wherein a belt conveyor transfers batches of tobacco particles from a main magazine into a wide upright duct. The level of different portions of the upper surface of the supply of tobacco in the duct is monitored by several photosensitive detectors which transmit signals for adjustment of a paddle wheel which removes surplus tobacco from the transfer conveyor by brushing off more or less tobacco from different portions of the conveyor, as considered transversely of the direction of movement of the conveyor, in order to maintain the entire upper surface of the tobacco supply in or close to a horizontal plane.