284 



BIOLOGY OF THE LABORATORY MOUSE 



Some years later (1924) Little and Strong (50) described, in some detail, 

 the behavior of two transplanted adenocarcinomas of the dilute brown (dba) 

 strain of mice, dBrA and dBrB. Strong and Little (81) had previously 

 shown that these two tumors, although apparently identical histologically. 



PARENT I. 



PARENT 2. 



SUSCEPTIBILITY 



NON-SUSCEPTIBILITY 



A B a C ALL PRESENT SUSCEPTIBILITY 



2 27 



SUSCEPTIBLE 



9 

 A B 



9 



B C 



V 



37 

 NON-SUSCEPTIBLE 



RATIO I* TO 1.3- PERCENT SUSCEPTIBLE 42.2 



Fig. 1 29. — Diagram showing the inheritance of susceptibility to transplanted tumors 

 where susceptibiHty is due to the simultaneous presence of three dominant genes. 



gave distinctly different percentages of successful growth when inoculated 

 simultaneously on opposite sides of the same animals. 



The results of inoculating these two tumors in a large number of dilute 

 brown mice, unrelated Bagg albino (A) mice and various hybrid generations 

 between them are shown in Table 5. 



With the exception of the backcross Fi X Bagg albino inoculated with 

 dBrB, the two tumors give figures which coincide closely with the expecta- 

 tion for two genes in the case of dBrB and three for dBrA (Table 6). 



