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AMERICAN JOURNAL OF BOTANY 
in which we should look for them. It is evident that their existence does not 
depend upon very high temperatures, but in the absence of extreme cold, 
and provided with copious and constant moisture, many species of tropical 
affinities may flourish in high latitudes. This fact has an important bearing 
on the question of changes in climate in earlier geological time. 
It would not seem necessary to assume any radical changes in the earth’s 
climate as a whole to explain the remains of warm-temperate types in the 
far north, where now conditions are impossible for their existence. Could 
we replace the existing continental conditions by an archipelago bathed 
by warm ocean currents, there is no reason why, in the northern hemisphere 
as in the southern, the plants of the lower latitudes should not extend their 
range toward the pole, far beyond their present limits. 
In conclusion, the writer would like to thank his botanical colleagues in 
New Zealand for the assistance of many kinds given him in his travels 
through the country; but he would also express his great appreciation of the 
kindness of various other gentlemen, official and otherwise, who helped to 
make his visit a very successful one. He feels under special obligation to 
Mr. J. D. Gray of Wellington, Secretary of the Department of Foreign 
Affairs. 
Stanford University 
EXPLANATION OF PLATE XXXVII 
Rain-forest, North Island. Nikau palm and tree-ferns. 
