42 



Dr. J. A. Murray. Cancerous 



[Mar. 22, 



equality of correlation exists, and whether the somatic resemblance can be 

 used as a test for predicting the consequences of inbreeding, are points 

 which must be left for future elucidation. 



(v) Some of the limitations of the method of this paper have been pointed 

 out, and others are obvious. The extension to the case where more than one 

 pair of allelomorphs is considered might conceivably be valuable when more 

 data have been collected, and should not prove difficult. 



In particular, a method which assumes the absence of selective mating 

 and ignores the existence of differential fertility can claim no finality. It is 

 hoped, however, that some of the conclusions are fairly exact deductions from 

 the simple Mendelian theory as it stands at the present time. 



In conclusion, I wish to thank Prof. Pearson for the help noted in the 

 paper, and for much stimulating criticism. 



Cancerous Ancestry and the Incidence of Cancer in Mice. 

 By J. A. Murray, M.D., B.Sc, Imperial Cancer Kesearch Pund. 



(Communicated by Prof. J. Eose Bradford, Sec. E.S. Eeceived March 22, — 

 Eead May 4, 1911.) 



The purpose of these experiments has been the collection of data 

 sufficiently abundant and accurate to determine whether an enhanced 

 liability to cancer is transmitted in the case of mice from parents to 

 offspring. In a preliminary note in 1909* a short account was given of the 

 manner in which these experiments have been conducted. 



The animals have all been housed and fed in a uniform manner in one 

 room. They have been kept in large cages, which have been cleaned 

 regularly, and the environment has been as uniform as it has been possible 

 to make it. During the past five years nearly 1600 animals have been bred, 

 the two sexes contributing approximately equal numbers. Of them, &62 

 females which have lived for six months or more form the materials of the 

 present paper. The incidence of the disease is so dependent on the age and 

 sex of the animals that, in order to get comparable groups, only mice of the 

 same sex and of approximately the same age may be reckoned together. 



* E. F. Bashford and J. A. Murray, " The Incidence of Cancer of the Mamma in 

 Female Mice of Known Age," ' Roy. Soc. Proc.,' 1909, B, vol. 81, p. 310. 



