the splashed-white Andalusian. When these are crossed 

 the progeny are blues, and when the blues are mated 25 per 

 cent, of the progeny are black, 25 per cent, are splashed- 

 white and 50 per cent, blues. (Fig 17). 



The following diagram shows the inheritance — 



Black X White P, 



Blue X Blue Fi 



1 Black 2 Blue I White . . F. 



The roan color of Shorthorn cattle is produced by cross- 

 ing white and red. Roan is heterozygous, for when roan is 

 mated with roan, of the progeny 25 per cent, are red, 25 per 

 cent, white and 50 per cent. roan. 



The following diagram shows the roan inheritance:— 



Red X White P, 



Roan X Roan F, 



■ \___ 



i ! I F. 



1 Red 2 Roan 1 White 



2 — Multiple Factors 



"The term' multiple factors' has come, in practice, to 

 be applied usually to cases of crossing in which two or more 

 factor-differences occur, all of which produce similar effects' ' 



(Morgan). 



Several examples of this type of inheritance have been 

 brought to light by Nilsson-Ehle of Sweden, and by ShuU, 

 Castle and East of the United States. 



(a) Nilsson-Ehle found that when a dark-brown oat with 

 dark glumes was crossed with a white-glumed oat, F, 

 were all dark brown, but Fo were 9 dark brown, (> 

 light brown and 1 white. This result is explained 

 on the assumption that the dark brown oat has two 

 dominant factors (A and B) for dark glumes and the 

 white-glumed oat two recessive allelomorphic factors 

 (a and b) for light color. The gametic segregation 

 in Fa may be represented as follows: — 



102 



) 



