84 A MANUAL OF MENDELISM 



If greys and duns be the result of single polygamous 

 factors, then there should be greys and duns of the 

 following constitutions : 



Greys Duns 



Gr Gr Gr Gr Gr Dn Bn Dn Dn 



Gr Dn By Bl Ch Dn By Bl Ch 



and each of these kinds should produce different assem- 

 blages of progeny when mated with themselves and the 

 other colours. So far as grey, which we shall consider 

 first, is concerned, the following phenomena should be 

 found : 



(i) There should be pure grey sires of the constitution 



p , and, with all colours of mares, these should leave 



grey foals only. As already stated, four such sires 

 have been found : 



(ii) Hybrid greys with hybrid greys, which, since 

 almost all greys are hybrids, means in ordinary expe- 

 rience greys with greys, should leave grey foals and 

 foals of other colours, and the former should be to 

 the latter in the proportion 3:1; for, since the parents 

 may be of any of the following constitutions ; 



