The unsaturated fatty acid fraction extracted from the liver of rabbit irradiated with X-rays exerts a strong cytotoxic effect on human coelothelioma cells and Yoshida sarcoma cells both in vitro and in vivo. The cell damage seems to initiate at the nucleus, finally leading to the
complete cytolysis. The inhibiting effect of this substance on the mitosis of Yoshida sarcoma cells can be observed, especially marked from prophase up to metaphase giving almost the same results obtained after X-ray irradiation. From these results and the observations reported by several authors on the cell damage by X-ray irradiation, weshould call special attention to the fact that the essential mechanism of X-ray irradiation can be
attributed to the cell toxin produced after the irradiation.</p
