xil 
CHAPTER 
DOMESTICATED ANIMALS AND PLANTS 
V. THE Way oF THE WILD 
The astonishing abundance of life — The saaie for exist- 
ence — Selective effect of the natural conditions — Competition 
for food — Competition for room — Competition most severe 
between individuals of the same species — Natural selection — 
Survival of the fittest — The individual and the race — Signifi- 
cance of numbers — Significance of vigor and length of life — 
Significance of offensive and defensive weapons — Significance 
of protective coloring and markings — Mimicry — Design in 
nature — Causes of color in animals and plants 
VI. Errect or NaTturRAL SELECTION 
Natural selection means progressive Aielgpaiente-s Effect af 
selection upon the individual — Selection good for the species 
that can endure it — Selection fatal to a race that cannot en- 
dure its hardships — Interest of the individual and the race 
not identical — A close fit between a species and its environ- 
ment is inevitable — Apparent exceptions due to absence of 
severe selection — Adaptation not necessarily perfect — Our 
standards of selection differ from those of nature — Not all the 
results of natural selection are useful to us — Our standards 
often require much readjustment of domesticated species — 
Natural selection always at work —VTower of selection to 
modify type 
VII. Unir CHARACTERS 
Unit of study — Species spin pases of definite characters — 
Every individual possesses all the characters of the race — 
Characters developed and characters latent — Characters 
dominant and characters recessive — Correlation of characters 
— Lost characters— New characters — Characters and unit 
characters 
VIII. VaRIABILITY OF A SINGLE CHARACTER 
Critical study of a single character — Types — Plotting the 
frequency curve — The mean — The typical individual — Vari- 
ability or deviation from type — Average deviation — Standard 
deviation — Coefficient of variability — Suggestions as to tak- 
ing measurements — Suggestions as to grouping — Sugges- 
tions as to numbers — Suggestions as to taking samples — 
Advantages of statistical studies 
TX. How CHARACTERS ARE TRANSMITTED . . . 2... 
Every species of its own kind — The machinery of transmis- 
sion — Fertilization — Fertilization in general — The material 
transmitted — Chromosomes — Development, or growth and 
differentiation — Termination to growth 
X. WHEN DEVELOPMENT GOES WRONG 
Differentiation with development — Uuienigisiieuk or 
dwarfing — Overdevelopment, or giants — Arrested develop- 
ment of a single character or part — Overdevelopment of a 
single part— Doubling of parts— Fusing of parts — When 
unit characters get misplaced — Abnormal growths 
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