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NOTICES OF NEW BOOKS. 35 
and their causes, considering that changes of climate have 
doubtless been agents of the first importance in modifying 
specific forms as well as affecting the distribution of animals. 
Step by step the foundation is laid for a scientific interpretation 
of the phenomena of distribution, until the reader reaches the 
second part of the work (pp. 283—512), which embodies the 
results of an investigation of a series of typical Insular Faunas 
and Floras, with a view to explain the interesting phenomena 
they present. 
Amongst other conclusions arrived at, Mr. Wallace argues, 
from the evidence which he adduces, that ‘mere distance is one 
of the least important of the causes which have determined the 
likeness or unlikeness in the animals of different countries ;” 
“that such differences and resemblances cannot be due to 
existing conditions, but must depend upon laws and causes to 
which mere proximity of position offers no clue ; ” and “that if 
we compare corresponding portions of different continents we 
find no indication that the almost perfect similarity of climate 
and general conditions has any tendency to produce similarity in 
the animal world.” 
In conclusion, Mr. Wallace expresses his conviction of the 
complete interdependence of organic and inorganic nature. ‘Not 
only,” he says, “does the marvellous structure of each organised 
being involve the whole past history of the earth, but such 
apparently unimportant facts as the presence of certain types of 
plants or animals in one island rather than in another are now 
shown to be dependent on the long series of past geological 
changes,—on those marvellous astronomical revolutions which 
cause a periodic variation of terrestrial climates,—on the 
apparently fortuitous action of storms and currents in the con- 
yeyance of germs,—and on the endlessly varied actions and 
reactions of organised beings on each other.” 
We close this volume with a sense of deep obligation to 
Mr. Wallace. Following his guidance, we have felt as one led 
by some “good fairy” to the top of a high mountain; we have 
looked down into the valleys beneath, and beyond across the 
great expanse of ocean with its many islands; we have seen 
passes, peaks, and glaciers while listening to the story of their 
origin; we have noted a marvellous variety of vegetation, and 
have become acquainted with many strange and curious animals, 
