22 Characteristics, Structure, Life of Trees 
unquestionably still going on, species increasing their field of 
distribution, and also changing their functions to meet 
changes in climate, or else succumbing and dying out 
through inability to adapt themselves. But this is a matter 
of long-continued evolution and very gradual change, in 
which thousands of individuals succumb while a few selected 
ones are adapted. Artificial acclimatization, therefore, is 
probably not, at least practically, within the means of man, 
as far as the long-lived arborescent forms are concerned, 
whatever may be accomplished with annuals, or even with 
shrubs, which send out new shoots from the root-stock 
annually. But transfer from one locality to another where 
the tree is not native has been practised successfully, the 
assumption being that the climate of the new location was 
favorable to the exotic newcomer. Whether or not such 
transfer may be successfully made is in general a matter of 
trial, climate being too complicated a matter to permit ready 
comparison and prediction of the adaptation of the plant 
to its new surroundings. We have only a few points for 
basing a judgment as to the probability of success. It is, for 
instance, not likely that a tropical species or one of southern 
warm latitudes will, as a rule, adapt itself to a northern 
climate. Species from moist climates are apt to succumb 
in dry ones. The nearer in temperature and moisture the 
climate is to that of the native habitat, the greater the likeli- 
hood of success in transplanting a species. 
Cases are known when the new environment has proved 
even more favorable to the development of exotics than to 
that of its native fora, as in the case of European species in 
California and in other parts of this continent. On the 
other hand, while a species so transferred may be able to 
live in the new surroundings it may develop differently from 
its habit in its native country. Again, some species have 
