Selecting for In -and -in -Breeding 147 



but it is not generally accepted that the good 

 or evil results are in proportion to the degree 

 of relationship between the animals mated. If 

 in-breeding is to be practiced, the degree of re- 

 lationship should not be the determining factor. 

 A more rational selection is based on the indi- 

 vidual merits of the animals to be mated. When 

 related individuals are to be bred together, the 

 selection should be made on the suitability of 

 the animals to each other and not wholly on the 

 degree of relationship. 



The safety with which in-and-in-breeding may 

 be practiced will depend largely on the skill that 

 is used in selecting the related animals that 

 are to be mated, and on the extent to which 

 the practice is carried. The skilful breeder will 

 be able to derive many benefits, and will cease 

 the practice before positive injuries accrue. It 

 may safely be asserted, as a general, rule, that 

 promiscuous or indiscriminate in-and-in-breeding 

 should not be practiced. 



Farmers sometimes select from their young 

 fowls the best cockerel to head the flock the 

 next year, and hold that as long as they are 

 breeding from their best stock, improvement should 

 follow. In so doing, they perhaps forget that the 

 weaknesses are all quite as likely to be multiplied 

 in the progeny as the desired characteristics. 



Cross-breeding. This may be defined as breed- 



