Principles of Heredity 117 



II. MENDEL AND THE CRITIC'S VERSION OF HIM. 

 The "Law of Dominance." 



I proceed to the question of dominance which Professor 

 Weldon treats as a prime issue, almost to the virtual con- 

 cealment of the great fact of gametic purity. 



Cross-breds in general, AB and BA, named above, 

 may present many appearances. They may all be indis- 

 tinguishable from A, or from B\ some may appear A's 

 and some It's ; they may be patchworks of both ; they may 

 be blends presenting one or many grades between the two ; 

 and lastly they may have an appearance special to themselves 

 (being in the latter case, as it of ten happens, "reversionary"}, 

 a possibility which Professor Weldon does not stop to 

 consider, though it is the clue that may unravel many 

 of the facts which mystify him now. 



Mendel's discovery became possible because he worked 

 with regular cases of the first category, in which he was able 

 to recognize that one of each of the pairs of characters 

 he studied did thus prevail and was "dominant" in the 

 cross-bred to the exclusion of the other character. This 

 fact, which is still an accident of particular cases, Professor 

 Weldon, following some of Mendel's interpreters, dignifies 

 by the name of the " Law of Dominance," though he 

 omits to warn his reader that Mendel states no " Law of 

 Dominance " whatever. The whole question whether one or 

 other character of the antagonistic pair is dominant though 

 of great importance is logically a subordinate one. It 

 depends on the specific nature of the varieties and in- 

 dividuals used, sometimes probably on the influence of 



