Janus green B and neutral red were used for vital staining of mouse splenic reticulum cells that have been described in the chapter Ⅰ and phagocytic activities were observed by carbon particle feeding. 1) With my estabished method, observation of vital staining of splenic reticulum cells were possible under condition avoiding deletrious effects of stain after various time intervals of culture. 2) Each type of reticulum cells which were classified in the chapter Ⅰ was characteristically separated by vital staining method. ⅰ) Neutral red granules and vacuoles increased in sine and number. On the other hand, janus green B granules decreased and/or vanished, in the stage of Ⅰ, Ⅱ and Ⅲ type of reticulum cells. These findings showed that type Ⅰ reticuum cells matured into type Ⅱand then type Ⅲ reticulum cells in this order. ⅱ) In the cytoplasm of type Ⅲ reticulum cells, markedly enlarged red vaculoes and phagocytized stainable materials were observed. 3) Some of the neutral red stainable materials were vaculoes induced by toxic effects of neutral red and janus green B stain. 4) Reticulum cells cultured over 120 hours were stained immediately and faded sooner, in contrast to reticulum cells in the relatively early stage. This phenomenon was thought to be related to the declining function of the cell. 5) By addition of carbon particles to medium, most of type Ⅰ and Ⅱ reticulum cells showed little phagocytic ability, but type Ⅲ reticulum cells manifested active phagocytosis so that their cytoplasm was filled with carbon particles. That was considered to be specific function to type Ⅲ reticulum cells.