BREEDING SYSTEMS 247 
of individuals related for one generation, while in-and-in breeding 
indicates those showing a longer period and closer degree of, rela- 
tionship. The two terms simply express a difference in the degree 
of relationship of the mated birds. Three ways in which it is 
possible to inbreed are: 
MALE 
Fig. 125.—Inbreeding chart showing distribution of inherited characters. The black 
represents the blood lines of the male, and the white the blood lines of the female. The 
solid black lines represent that a male has been chosen from the group from which they 
start and the dotted lines that a female has been chosen. Inbreeding is traced through 
four generations and the results are shown at the bottom of the chart. 
1. Breeding sire and daughter, which produces progeny with 
one-fourth blood like the mother. 
2. Breeding son and mother, which gives progeny with three- 
fourths blood like the mother. 
3. Breeding brother and sister, which produces progeny with 
blood lines from both sire and dam in equal proportion. This 
latter method is undesirable in general practice (Fig. 125). 
