关键词: 钝化作用, 显影诱导期, 照相显影

Abstract: A phenomenon which we call "passivation of development center" was described.Different from normal development center,this kind of development center shows low development activity and is not capable to initiate the reduction of grain immediately.The evolution of development center from "passive" to "active" needs a certain interval of time.The longer the duration of this interval the longer the induction period.The causes of the formation of passive development center was discussed and attvibuted to the role of silver-gelatin shell in the early stage of development.

Key words: Passivation, Induction period, Gelatin