VII 



POLYGAMOUS FACTORS 



In the last chapter it was stated that five true-breed- 

 ing cattle colours are known. Two only behave as 

 dominant and recessive — black being dominant to 

 red — the others produce intermediate hybrids. So far 

 as yet known, the following table gives the pure-breeding 

 parent colours and the hybrids they produce : 



Parents 



Hybrids 



In this table three anomalies are obvious : first that 

 there are five true-breeding groups — an impossible 

 number ; second, that, since black differs from each of 

 the other colours in one pair and, so, reveals four pairs 

 of characters in operation, there are no more than five 

 true-breeding groups in all ; and third, that the colours 



70 



