THE GEOGRAPHICAL DISTRIBUTION OF FORESTS 73 
country may be developed to the highest pitch of pro- 
ductiveness, with the least waste of energy and time. 
Conservatism in such matters is a loss to ourselves 
and to posterity. 
Natural distribution of species, as it stands to-day, 
is mainly a matter of accident. The locust, red-oak, 
and Douglas-fir are as well, if not better known in 
Europe than in their native land. It is said by the 
foresters in Hungary that “the locust has been discoy- 
ered in America especially for the Hungarian plain.” 
The eucalyptus of Australia is at home in California, 
the ailanthus and paulownia come to us from the 
Orient, and a visit to many arboreta in tropical as 
well as temperate regions should convince us that 
experimentation with exotics is in its merest infancy. 
In order to understand the peculiar groupings of 
plants in societies over the face of the earth, we must 
consider the various agencies of, and drawbacks to, 
the extension of vegetation. There is a tendency 
toward a settled equilibrium, but just as long as the 
forces of extension and interruption are inconstant 
and sporadic, just so long will the ranges of the vari- 
ous species change. The idea of a natural range of an 
economic plant no longer means much, and is no 
longer of much importance, except as a matter of his- 
tory. Few people are concerned with the natural 
range of the locust-tree. Its possible range is of much 
