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 chmate, 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 probabiHty 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 en^•ironment has proved 

 even more favorable to the development of exotics than to 

 that of its native flora, 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 



