RESULTS OF HYBRIDISATION 385 



It has been stated in some cases, — (a) that the hybrid shows 

 more of the character of that parent which is phyletically older 

 or more securely established— see e.g. some of the results of Stand- 

 fuss ; (b) that the hybrid shows more of the character of that 

 parent whose gametes were relatively more mature at the time 

 of fertilisation—^, some of the results of Vernon. Other 

 generalisations have been ventured, but all require to be 

 revised in the light of what we now know of Mendelian 

 phenomena. 



It remains to be seen how far the known cases of blended, 

 exclusive, and particulate inheritance are interpretable as forms 

 of Mendelian or alternative inheritance, and there are many 

 who suspect that the result will be the great extension of the 

 Mendelian interpretation. Until we have wider knowledge of 

 unit characters and of their alternative inheritance we must 

 retain the descriptive terms- — blended, exclusive, and particulate. 

 In many cases where there is a pairing of closely similar organisms, 

 the most striking fact is the uniformity of the inheritance — 

 which we might describe as continuous. 



It may seem strange, at first sight, that there can be any 

 question of bringing a " blend " within the Mendelian category. 

 But where we have to deal with a multiplicity of independent 

 characters, some dominant on the paternal side, some on the 

 maternal side, the impression that there is blending in the off- 

 spring may readily arise, and still more when we come to the 

 mixtures in the next (F a ) generation. 



What is called particulate inheritance may be due to the 

 alternative inheritance of the elements of a patchwork of char- 

 acteristics, which, as Galton said, " are usually transmitted in 

 aggregates, considerable groups being derived from the same 

 progenitor." He went on to say : " Skin-colour is a good 

 example of what I call blended inheritance. It need be none 

 the less ' particulate ' in its origin, but the result may be 

 regarded as a fine mosaic too minute for its elements to be 



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