HEREDITY AND VARIATION 



generation may be of three kinds in respect of 

 any given character. Some of them will be white, 

 since they were formed by the union of a white- 

 bearing gamete from each parent, some black 

 since formed by the union of two black-bearing 

 gametes, and some gray like their gray parents, 

 since formed by the union of a black with a white 

 gamete. But the gametes of this new gray individ 

 ual will not be gray, but black or white, as before. 

 If this is unintelligible, I can only express my regret. 

 /This discovery that variation e.g., the produc 

 t/on of a black individual from gray parents 

 isi really a form of heredity, proceeding according 

 to definite laws, instead of being a sort of &quot;bad 

 shot&quot; at heredity, clearly marks a new epoch in 

 our conceptions of the subject. The above asser 

 tion of the working of the process constitutes 

 Mendel s &quot;law of segregation.&quot; 



Let us observe some of the consequences. We 

 now know that new species can and do arise by 

 the operation of the laws of heredity quite apart 

 from any slow accumulation of variations under 

 the influence of natural selection. As Professor 

 Bateson says: &quot;The dread test of natural selection 

 must be passed by every aspirant to existence, 

 however brief&quot;; but that expresses the totality 

 of its power. Observe further that the scholastic 

 dictum, natura non facit saltum, which has so long 

 been believed, cannot hold. Nature does sometimes 

 make leaps ; and the modern belief in discontinuous 

 variation is a denial of the old dogma. 



