CHAPTER 
CONTENTS 
XI. How CHaRACTERS BEHAVE IN TRANSMISSION . 
Characters tend to combine in definite mathematical propor- 
tions — 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 hybridiza- 
tion complicated — Mutation and mutants— Origin of new 
and improved strains 
XII. How THE OFFSPRING COMPARES WITH THE PARENT, 
OR DESCENT WITH MODIFICATION 
The complex nature of heredity — The offspring not like the 
parent — Mediocrity the common lot, whatever the parentage ; 
regression — Some offspring better and some worse than their 
parents — The exceptional parent and his offspring — Pro- 
gression — The exceptional offspring and his parent — Rever- 
sion — Degeneracy 
XIII. THe Law or ANCESTRAL HEREDITY 
The extent to which the offspring resembles the parent and 
the extent to which he resembles more remote ancestors — 
Chance of resembling a particular individual ancestor — The 
individual a composite — The number “two” 
XIV. HEREDITY AND ENVIRONMENT 
Mistaken estimate of environment — All the characters of the 
race, both good and bad, are transmitted to the individual by 
his parentage— The function of environment is to assist or 
to hinder in development — Environment does not add unit 
characters — Modifications due to environment 
XV. SysTEMATIC IMPROVEMENT OF ANIMALS 
ee 
Origin of the “ pure bred” — Pedigree registers — Advanced 
registry — Unregistered stock and scrubs — Systems of breed- 
ing — Source of sires— Herd improvement and breed im- 
provement — Rational improvement — Choosing the breed — 
Breed differences slight— Market classes and grades — 
Knowledge of market requirements needful 
XVI. Systematic IMPROVEMENT OF PLANTS 
Improvement by selection — Crossing to produce new varieties 
— Application of Mendel’s law in crossing — Separation of the 
desired character — Behavior of the recessive — Behavior of 
the dominant — When more than two characters are involved 
— Systems of planting —Records 
Xill 
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