EVOLUTION BY LOSS . 



the corresponding yellow variety in the same 

 cross. 



In addition to the modification which pro- 

 duces yellow varieties, we can recognize sev- 

 eral other modified conditions of the unit- 

 characters A, B, C, and Br, which modifica- 

 tions produce whole series of color varieties. 

 For a modified condition of a single unit- 

 character is capable of producing as many 

 new varieties as there are possible combina- 

 tions of the modified character with other unit 

 characters. 



One who attends a poultry-show cannot fail 

 to be impressed with the great number of color 

 varieties among poultry. Let him first observe 

 these among fowls of common size, and if he 

 then visits the bantam section he will find them 

 all duplicated in miniature among the bantams. 

 If a new color variety is brought out, it is only 

 a short time until it finds its place among the 

 bantams as well as among fowls of common 

 size. The dwarf size of the bantam is clearly 

 due to a modified condition of one or more unit- 

 characters capable of combinations with as many 

 different kinds of coloration as occur among 



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