The Making of Species 
The ordinary Mendelian pictures a unit 
character in a cross that obeys Mendel’s law, 
as follows =e the dominant character only 
showing. It seems tous 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 RODS, 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 RUD}. When such recessives 
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 RIBS 
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 
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