Under the proper stimulus the cells of many plant species, including tobacco, possess highly developed regenerative powers. When such pluripotent cells are transformed by the tumor-inducing principle associated with the crown-gall bacterium, the resulting tumor cells may retain indefinitely a well developed capacity for organizing buds. Adventitious shoots derived from such tumor buds were forced into fast growth by a series of graftings to healthy plants. When these tumor cells were thus made to grow and divide very rapidly, they recovered and became normal in every respect. This finding suggests that the factor which causes crown-gall tumor cells to develop abnormally becomes diluted in and is eventually lost from affected cells that are forced to grow and divide with sufficient rapidity.

The regenerative competency of the host cells acted upon by the tumor-inducing principle at the time of their alteration appears to be decisive in determining the type of tumor that will result. Although the cytological system through which the potentialities of a cell manifest themselves is not known, the results reported here indicate that polarity plays an important part.

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