Voi^. 6, 1920 
PATHOLOGY: J. B. MURPHY 
35 
Critical points : 
\l, = 1.076 =t 0.005 A, approximately = X^,; 
= 0.935 ± 0.004 A, approximately = X^,; 
^Li» ^iid Xx,3 are probably exactly equal to X^^, X^^ though 
more work is needed on this point. 
Intensity ratios : constant for any pair of lines of the same series, with 
changes in voltage, as far as they have been investigated. 
1 Webster, D. L., and Clark, H., these Proceedings, 3, 1917 (181-185). 
2 Dershem, E., Physic. Rev., Ithaca, 1 1, 1918 (461-476). 
3 Overn, O. W., Ihid., 13, 1919 (137-142). 
* Webster, D. L., Ihid., 9, 1916 (599-613). 
5 De Broglie, M., and Lindemann, F. A., C. R. Acad. Sci., Paris, 158, 1914 (944); 
de Broglie, M., /. Physique, Paris, 4, 1914 (265-267); see also independent invention 
by Rohmann, H., Physik. Zs., Leipzig, 15, 1915 (510-512). 
6 Siegbahn, M., and Friman, E., Phil. Mag., London, 32, 1916 (39-49) ; or Siegbahn, 
M., Jahrh. Radioakt. Elektronik, Aachen, 13, 1916 (296-341). 
7 Hull, A. W., G. E. Review, Schenectady, 19, 1916 (173-181). 
8 Blake, F. C, and Duane, W., Physic. Rev., Ithaca, 10, 1917 (625). 
9 Birge, R. T., Ihid., 14, 1919 (361-368). 
10 Duane, W., and Shimizu, T., Ihid., 14, 1919 (67-73). 
" De Broglie, M., /. Physique, Paris, 6, 1916 (161-168), with an addition of 1.5' 
to all angles as advised by him in a personal communication. 
12 Wagner, E., Ann. Physik, Leipzig, 46, 1915 (868-893). 
^3 Calculated from Siegbahn and Friman 's wave-lengths of other lines. 
14 Duane, W., and Shimizu, T., these Proceedings, 5, 1919 (198-200). 
THE EFFECT OF PHYSICAL AGENTS ON THE RESISTANCE 
OF MICE TO CANCER 
By James B. Murphy 
RocKEFEi,i.ER Institute for Medicaid Research, New York City 
Read before the Academy, November 10, 1919 
The report which I wish to present today has to do with further progress 
in the work which I reported before the Academy in June, 1915. I will 
review that work briefly in order to orient you with the observations made 
since then. 
The fundamental point in immunity to transplanted cancer is that there 
are two types of resistance, the so-called natural and induced immunity. 
Mice may be rendered resistant by an injection of a quantity of homologous 
living tissue given at least a week or ten days before the cancer inocula- 
tion; this is called induced immunity. A variable proportion of mice 
inoculated with a transplantable tumor will be resistant; this is called 
natural immunity. The histological manifestation of resistance about 
an introduced cancer graft in these two types of immunity is the same and 
