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BY SIDNEY I. SMITH. 

Ir is one of the ever-wise provisions of nature, that every _ 
land has a vegetation and an association of animals peculiar — 
to itself, that every sea and every zone of ocean is peopled — 
with life found nowhere else. There is such a wealth of — 
conception in the forms of organic life, that there is no need — 
of their repetition in distant lands. The palms and the reef — 
corals never wander from the tropics; the humming-birds — 
are as peculiarly American, as the Mississippi or the Andes. — 
It is specially the province of modern science to explain the 
phenomena of nature on known natural laws and forces, and — 
with this view no phenomena are more interesting than those — 
of the geographical distribution of species. The subject, in 
its full extent, would involve a solution of the much-vexed — 
question of the origin of species; but whether species now — 
living were derived from their relatives of a former geologi- — 
cal age, or were independently created, we will not question © 
in the present article, only taking species when they first 
appeared as they now exist, and contenting ourselves with — 
some of the more prominent forces which bind them to pe- a 
culiar habitats, or tend to diffuse them over wider or differ- — 
ent areas. q 
These secondary causes, which act in the geographical dis- — 
tribution of species, are either inorganic or organic. Of the 4 
former the most important are the influences of topography 3 
temperature, ocean currents, winds, and humidity ; of the lat- 
ter, animals themselves, and man,—for in this respect man- 
must be separated from the mere brute animals as wielding a- 
very different influence. The inorganic forces are so inte 
woven, they so act and react upon and limit each other, that 



one of the subjects assigned inet eines fi th R bet m i g th atrai ata Qatari 
tific School of Yale College in 1867. 
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