1. In order to observe a certain function of the Russell's cell as well as other free cells in the coelomic fluid of newts, phagocytotic activities were induced by means of single inoculation of diluted India ink into the body cavity.
2. Active phagocytotic activity was observed in monocytes, large lymphocytes, neutrophilic granulocytes and macrophages in the first week of the treatment.
3. Although Russell's cells did not ingest carbon particles of the ink, carbon-bearing Russell's cells gradually appeared in the preparations of the first week, and then the number increased at the third week.
4. There was a notable decrease in appearance of the carbon-bearing Russell's cells thereafter. This phenomenon would indicate that progressive decline of mature type of Russell's cells occurred within 2 months.
5. From the observation of all types of free cells which ingested the carbon particles and the results of the investigation of changes in number of carbon-bearing Russell's cells supported the supposition of a possible cellular transformation of Russell's cells from monocytes or lymphocytes through the young type of Russell's cells.