Abstract: The behavior of the light induced electron and the reducing agent electron in direct positive emulsions was studied. The locations of the fog centers preferably formed in the grain introduced by light are different from those introduced by reducing agents. When photofogged the fog centers are formed in the interior of the grain first indicating that the light induced electrons can enter the conduction band directly. Wherease, when fogged by reducting agents, the internal fog centers are formed only when the quantity of reducing agent is sufficient and after the formation of surface centers. In above two cases the ways in which electrons enter the conduction band of silver halide are different.

Key words: light induced electron, reducing agent electron, fog center