The facts to be explained--The conditions which have determined distribution--The permanence of oceans--Oceanic and continental areas--Madagascar and New Zealand--The teachings of the thousand-fathom line--The distribution of marsupials--The distribution of tapirs--Powers of dispersal as illustrated by insular organisms--Birds and insects at sea--Insects at great altitudes--The dispersal of plants--Dispersal of seeds by the wind--Mineral matter carried by the wind--Objections to the theory of wind-dispersal answered--Explanation of north temperate plants in the southern hemisphere--No proof of glaciation in the tropics--Lower temperature not needed to explain the facts--Concluding remarks
CHAPTER XII · THE GEOGRAPHICAL DISTRIBUTION OF ORGANISMS
From Darwinism: An Exposition of the Theory of Natural Selection by Alfred Russel Wallace.
