SOME NEW PRINCIPLES 241 



tlie breeder on which the present available infor- 

 mation is very scanty. It is the simple question of 

 the inheritance of bulk. In the pea, for instance, there 

 is a race with a seed as large as that of Victoria 

 Marrow, and also a race with a seed half its size, 

 as in some of the continental field peas. Now these 

 two char act erisers, " large " and " small," do not 

 constitute the two members of a Mendelian pair ; 

 the cross between them is a blend, and so far as 

 data at present available show, segregation does 

 not occur when the hybrids are self-fertilised. If 

 one of these " small " races possessed, as one of them 

 happens to do, an economically valuable character, 

 and if it is desired to combine this character with 

 " large " size in a single strain, this would be an easy 

 matter if " large " and " small " constituted the 

 members of a Mendelian pair. But as — or let us say, 

 supposing — they are not, we cannot proceed to effect 

 this combination until the mode of inheritance of these 

 two characters has been determined. The most im- 

 portant point to discover in such an inquiry would be 

 to determine which, if any, of the types in the second 

 hybrid generation bred true. This generation might 

 consist of a complete series of gradations between 

 a " small " identical with the pure " small " at one 

 end, and a " large " identical with a pure " large " 

 at the other end ; and it might possibly be that these 

 two extremes of the series bred true, that the blends 

 in the middle of the series never did, and that the 

 forms intermediate between the blends and the 

 extremes bred true in some individuals and not in 

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