A Cinematographical Studies of Cellular Slime Molds I

A 16mm cinematographical analysis was made on the early process of culmination of Dictyostelium discoideum. The present study revealed that the stalk, formed at the top of cell mass, elongated down to the base. The head of the cell mass would then start an upward motion as soon as the tip of the stalk reached into the presumptive disk cells. The stalk pushed downward remarkably fast and it took only ten minutes for the tip of the stalk to reach the base. A combination of the pushing down of the wedge-like stalk and the motion of the sheath as if squeezing seemed to raise the cell mass. The disk was formed also by an downward motion of the sheath. The stalk becomes fixed, and a stable disk covered with the sheath was thus completed by this formative movement.