By performing the roller-tube tissue culture of Bashford's cafcinoma the author observed cells in culture under a phase-contrast microscope after fixing and staining them variously and by taking their pictures with a 16mm-movie camera; and obtained the following results. 1. Cancer cells in culture possess various morphological characteristics so that they can be readily distinguished from fibroblasts and histiocytes. 2. It has been recognized that mitochondria, nuclei, and nucleoles of the cancer cells in culture possess motive power. 3. In the observation on the cell division of cancer cells in culture the prolongation of the cell division at the metaphase as compared with normal cells can be recognized the same as in other tumor cells. 4. Isolated cancer cells have been recognized to possess the motive power, revealing the maximum wandering velocity of 1.9 μ/min and the average velocity of 0.6 μ/min. In addition, a mass of several cancer cells has been observed moving from place to place as a whole. 5. Cancer cells are vitally stained with neutral red and Janus green, and irregular swelling and disarrangement of vitally stained granules can be observed. 6. However, no carbon-particle phagocytiticle phagocytotic ability can be recognized in cancer cells.