328 THE SURVIVAL OF THE UNLIKE. [xiX. 



fer the pheuomena directly to acclimatization, as we 

 are unable to determine positively whether or no 

 the common apple is indigenous to Russia. But 

 here are great adaptations to climate, which might 

 have been brought about by disseminations made 

 through the agency of man, as well as those made 

 by nature. According to Buysman,* the cultivated 

 apple grows in Norway at a latitude of sixty -five de- 

 grees twenty -eight minutes, while the wild apple grows 

 only as high as sixty -three degrees forty minutes ; in 

 Finland the cultivated apple occurs at sixty -three 

 degrees, the wild only at sixty degrees. Schiibeler 

 states that while the pear is unknown in a wild state 

 in Norway, it is cultivated as far north as Trondhjem, 

 latitude about sixty -four degrees. The cherry is not 

 certainly known in an original wild condition, yet it 

 is cultivated as f^r north as the polar circde in the 

 open ground.! These extensions of cultivated plants 

 to the northward are not proof of acclimatization, as 

 in nature the limits of species are often determined 

 by other agencies than climate. Yet the instances 

 cited are indicative of such change. A singular in- 

 stance of the adaptation of the apple is stated by Mr. 

 T. T. Lyon, who found that apples from the south- 

 ern states are hardier in Michigan than many kinds 

 of northern origin. This anomaly is perhaps due to 

 the inuring of the trees to the trying southern sum- 

 mers, enabling them to endure our severe northern 

 droughts, so that they enter the winter with unim- 

 paired constitutions. 



*Am. Jour. Sci., 3rd ser. xxviil,355. 



t Geographische Verbreitong der Obstbaume uud BeereutraKendeu Oeitriluche 

 In Norwegen, 28, 29. 



