THE PROBLEMS IN MATING AND IN E(IG PHODUCTION 131 



number 1 is mated with male mimber 2, having produced 

 group number 3, which is one-half the blood of the sire and 

 dam. 



Females from group number 3, mated to their own sire 

 number 2, have produced group number 5, which is three- 

 fourths of the blood of the sire number 2 and one-fourth the 

 blood of the dam number 1. 



Fig. 43. — The Felch breeding chart. Line breeding. 



A male from group number 3, mated back to his own dam, 

 number 1, produces group number 4, or vice versa, which will 

 produce group number 7, which is mathematically half the 

 blood of each of the original pair, numbers 1 and 2. This is a 

 second step toward producing a new strain. 



Females from number 8, mated back to the original male, 



