The Making of Species 



The ordinary Mendelian pictures a unit 

 character in a cross that obeys Mendel's law, 



as follows : ^ the dominant character only 



showing. It seems to us that each unit character 

 should be represented as a double entity, thus 

 D(D), the portion within the bracket being 

 latent. The cross would appear to be repre- 

 sented by the formula -o/pv\ since the union 



appears to take the form of the transfer of 

 the dormant latent characters. Now an ex- 

 tracted pure recessive will, on this hypothesis, 



bear the formula T>/T\\ When such recessives 

 R(D). 



are crossed the two dormant portions will 

 ordinarily change places, and never appear, so 

 that these extracted recessives will, under 

 ordinary circumstances, appear to be as pure 

 as the true pure recessives, which are represented 



by the formula D \- D { 

 K(K). 



Now, suppose that, from some cause or other, 

 it is possible for the latent D to change places 

 with the visible R, it is obvious that the impure 

 nature of the extracted and hitherto apparently 

 pure recessives will become manifest. This 

 seems to be what happens under certain circum- 

 stances to the extracted albino mice. They 



