Characteristic Temperatures in Super-Novae.

750 required to kill the tumor while in the case of neutron rays only = 2.9 times the 260 mouse lethal dose produces the same tumor effect. This comparison of dosage ratios indicates that neutron rays may be more selective than x-rays in their effects on this tumor. We are indebted to Dr. Francis Carter Wood for specimens of Sarcoma 180, and to Dr. R. S. Stone for his interest and for the x-ray facilities. One of the authors (P. C. A.) participated in this work through the award of a Fellowship by the Committee of the Christine Breon Fund of the University of California Medical School. We gratefully acknowledge also that these experiments have been made possible by the support of the Josiah Macy, Jr., Foundation, the Research Corporation and the Chemical Foundation. 1 Lawrence, John H., and Lawrence, Ernest O., Proc Nat. Acad. Sci., 22, 124 (1936). 2 Zirkle, Raymond E., and Aebersold, Paul C., IbU., 22, 134 (J9O6). s Lawrence, E. O., and Livingston, M. S., Phy. Revie, 4, 19 (1932). 4Whipple, Geo. W., and Warren, Stafford L., Jour. Rxp. Med., 35, 187 (1922). 6Wood, F. C., Radiology, 5, 199 (1925). * Packard, C., Am. Jour. Cancer, 16, 1257 (1932). 7Sugiura, Kanematsu, Am. Jour. Roent. and Radium Therapy, 31, 614 (1934).