INHERITANCE OF CANCER IN MICE 

 DE. LEO LOEE 



The Department ok Comparative PATii..r.n.n . AVa<iiin,; i ox ITntver- 



Ix the following we shall give a i^iiiiiinary of our in- 

 vestigations into the part heredity plays in the origin 

 of cancer. Our interest in this problem dates back a con- 

 siderable number of years. In 1899, in conjunction with 

 Dr. Jobson, we made our first observations on the en- 

 demic occurrence of cancer at the Stockyards in Chicago. 

 At that time we found cattle coming from a certain ranch 

 in Wyoming especially prone to have cancer at the inner 

 canthus of the eye (1). A few years later we observed 

 an endemic occurrence of sarcoma of the thyroid in a 

 family of rats. In this case we pointed out that the cir- 

 cumstances under which these sarcomata originated 

 pointed to a hereditary condition rather than to an in- 

 fection. At that time (1904)^ we referred to the de- 

 sirability of investigating oxporimentally' this endemic 

 occurrence of cancer (2) and we liad particularly in mind 

 an analysis of the etiological ta('t(»i- in breeding establish- 

 ments of mice or rats. Such an opportunity presented 

 itself a few years later hi the l)reeding establishment of 

 Miss Lathrop in Granby, Mass. A preliminary investi- 

 gation here revealed the fact that cancer occurred with 

 much greater frequency in certain inbred strains than in 

 others, and that no indications wdiatever could be found 

 of cage infection or direct infection from animal to an- 

 imal. We concluded in 1907 on the basis of these ob- 

 servations that there existed a hereditary predisposition 

 which was responsible for the endemic occurrence of 

 cancer (3). At that time we planned further much more 

 extensive experiments on the mode of hereditary trans- 

 mission of cancer in follosvinu- i^.latcd families and 

 strains of mice thronu'li several ovm-rations and in studj^- 



