CONTENTS. xi 
PAGE 
Stereometrical Fundamental Forms of Crystals and of Organisms.— 
Organic and Inorganic Forces.—Vital Force.—Growth and Adapta- 
tion in Crystals and in Organisms. — Formative Tendencies of 
Crystals.—Unity of Organic and Inorganic Nature.—Spontaneous 
Generation, or Archigony.—Autogony and Plasmogony.—Origin of 
Monera by Spontaneous Generation.—Origin of Cells from Monera. 
—The Cell Theory.—The Plastid Theory.—Plastids, or Structural- 
Units.—Cytods and Cells—Four Different Kinds of Plastids «. 316 
CHAPTER XIV. 
MIGRATION AND DISTRIBUTION OF ORGANISMS. CHOROLOGY 
AND THE ICE-PERIOD OF THE EARTH. 
Chorological Facts and Causes.—Origin of most Species in one Single 
Locality.— Centres of Creation.”—Distribution by Migration.— 
Active and Passive Migrations of Animals and Plants.—Means of 
Transport.—Transport of Germs by Water and by Wind.—Con- 
tinual Change of the Area of Distribution by Elevations and 
Depressions of the Ground.—Chorological Importance of Geological 
Processes.—Influence of the Change of Climate.—Ice or Glacial 
Period.—Its Importance to Chorology.—Importance of Migrations 
for the Origin of New Species.—Isolation of Colonists.—Wagner’s 
Law of Migration.—Connection between the Theory of Migration 
and the Theory of Selection—Agreement of its Results with the 
Theory of Descent eee ase eee eve tee eee ove BOO 
