A device for transferring toner along a flow path extending sequentially through an upstream stirring chamber(s) and a downstream stirring chamber(s). Toner transfer control apparatus controls toner transfer into the flow path, and a transfer of a developer including toner and a carrier between and from the upstream stirring chamber(s) to and between the downstream stirring chamber(s) to the latent image carrier whereby toner density along the flow path is controlled such that (i) a weight percentage of toner relative to developer in the upstream stirring chamber(s) is equal to or less than a first threshold value governing a time required to uniformly charge the toner; and (ii) the weight percentage of the toner to developer in the downstream stirring chamber(s) is greater than the first threshold value and equal to or less than a second threshold value necessary for the avoidance of uncharged toner.