" BLENDING " INHEEITANCE 



eared stock, to avoid ill-effects of inbreeding, 

 the size could have been still further increased, 

 with judicious selection doubtless up to the ex- 

 treme size of colored lop-eared rabbits. 



The general conclusion to be drawn is that 

 in attempting to combine in one race by cross- 

 breeding characters which exist separately in 

 different races, one should first inquire very 

 carefully how each character, in which the races 

 differ, behaves in transmission, for on the an- 

 swer to this question should depend the mode 

 of procedure to be chosen. 



If simple Mendelian characters only are con- 

 cerned, nothing is required but to cross the two 

 races and select from the second generation 

 offspring the desired combination. If blending 

 characters only are concerned and F yields 

 the desired blend, this is secure without fur- 

 ther procedure, except possibly selection to re- 

 duce its variability; but if the desired blend 

 is not yet secured, further back-crossing with 

 one race or the other may be necessary. If, 

 finally, both blending and Mendelian characters 

 are simultaneously involved in a cross, then the 

 method of combined line-breeding and selec- 



141 



