CHAPTER XI 
HOW CHARACTERS BEHAVE IN TRANSMISSION 
Characters tend to combine in definite mathematical proportions . Characters 
that do not blend: Mendel’s law of hybrids. Dominant and _ recessive 
characters: Pure races may spring from crossing- Very few individuals 
pure- A second method of improvement. Improvement by hybridization 
complicated - Mutation and mutants - Origin of new and improved strains 
The manner and machinery of transmission are exceedingly 
simple, but the mystery is, how so many and such different unit 
characters are contained in so small a bit of living matter, for 
that is all that passes over from parent to offspring. Many 
ingenious theories have been offered in explanation, but the 
mystery itself has never yet been solved. We do know much, 
however, of what in the end really happens, and in that, after 
all, the chief practical interest lies. - 
Characters tend to combine in definite mathematical propor- 
tions. In the.case of the white and yellow corn, for example, 
if a yellow silk is fertilized by a white pollen grain, the resulting 
kernel will be a ‘“‘ half blood”’ ; that is, one half its color tenden- 
cies will be yellow and one half white. If such a kernel now be 
planted where its progeny will again be fertilized by white pollen, 
the result will be a three-fourths white and one-fourth yellow 
generation. If the same be done again, the next generation 
will have seven eighths of the white “blood” with only one 
eighth remaining of the yellow, and so on indefinitely in regularly 
increasing and decreasing proportions. Of course the opposite 
result, but on the same plan, would have followed if the half 
blood had been bred successively with yellow rather than with 
white varieties. 
Having found the principle, we can readily calculate the 
“blood” of the progeny of any known mixture. For example, 
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