I. 
ON THE LAW WHICH HAS REGULATED 
THE INTRODUCTION OF NEW SPECIES.* 
Geographical Distribution dependent on Geologic 
Changes. 
Every naturalist who has directed his attention to 
the subject of the geographical distribution of animals 
and plants, must have been interested in the singular 
facts which it presents. Many of these facts are quite 
different from what would have been anticipated, 
and have hitherto been considered as highly curious, 
but quite inexplicable. None of the explanations 
attempted from the time of Linneus are now 
considered at all satisfactory; none of them have 
given a cause sufficient to account for the facts 
known at the time, or comprehensive enough to 
include all the new facts which have since been, and 
are daily being added. Of late years, however, a 
great light has been thrown “upon the subject by 
geological investigations, which have shown that the 
present state of the earth and of the organisms now 
*® Written at Sarawak in February, 1855, and published in 
the “ Annals and Magazine of Natural History,” September, 
1855. 
B 
