vill ANIMAL LIFE 
CHAPTER 
ment, 84.—The laws or general facts of development, 86.—The 
significance of the facts of development, 89.—Metamorphosis, 
90.—Metamorphosis among insects, 90.—Metamorphosis of the 
toad, 94.—Metamorphosis among other animals, 96.—Duration of 
life, 101.—Death, 108. 
VI.—THE PRIMARY CONDITIONS OF ANIMAL LIFE. eo * 
Primary conditions and special conditions, 106.—Food, 106.— 
Oxygen, 107.—Temperature, pressure, and other conditions, 108. 
—Ditfference between animals and plants, 111.—Living organic 
matter and inorganic matter, 112. 
VII.—THE CROWD OF ANIMALS AND THE STRUGGLE FOR EXIST- 
ENCE . = i 3 . F ‘ ‘5 
The crowd of animals, 114.—The struggle for existence, 116. 
—Selection by Nature, 117.—Adjustment to surroundings a re- 
sult of natural selection, 120.—Artificial selection, 120.—Depend- 
ence of species on species, 121. 
VIII.—ADAPTATIONS . i . . a q ‘ 
Origin of sdngaueness 128. afilasattiation of adaptations, 123. 
—Adaptations for securing food, 125.—Adaptations for self-de- 
fense, 128.—Adaptations for rivalry, 185.—Adaptations for the 
defense of the young, 1387.—Adaptations concerned with sur- 
roundings in life, 143.—Degree of structural change in adapta- 
tions, 146.—Vestigial organs, 147. 
IX.—ANIMAL COMMUNITIES AND SOCIAL LIFE s . ‘ c 
Man not the only social animal, 149.—The honey-bee, 149.— 
The ants, 155.—Other communal insects, 158.—Gregariousness 
and mutual aid, 163.—Division of labor and basis of communal 
life, 168.—Advantages of communal life, 170. 
X.—CoMMENSALISM AND SYMBIOSIS . : 3 ‘ ‘ a 
Association between animals of different species, 172.—Com- 
mensalism, 173.—Symbiosis, 175. 
XI.—PaRASITISM AND DEGENERATION . ‘i s . r 
Relation of parasite and host, 179.—Kinds of parasitism, 180. 
—The simple structure of parasites, 181—Gregarina, 182.—The 
tape-worm and other flat-worms, 183.—Trichina and other round- 
worms, 184.—Sacculina, 187.—Parasitic insects, 188.—Parasitic 
vertebrates, 193.—Degencration through quiescence, 193.—De- 
generation through other causes, 197.—Immediate causes of de- 
generation, 198.—Advantages and disadvantages of parasitism 
and degeneration, 198.—Human degeneration, 200, 
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