326 THE SURVIVAL OP THE UNLIKE. [xiX. 



north from southern seeds are often much more ten- 

 der than those grown from northern seeds of the 

 same species. While this fact is generally proof of 

 acclimation rather than of acclimatization, it never- 

 theless indicates clearly enough that acclimatization 

 could take place after the lapse of sufficient time. 

 Concerning this matter, the veteran Robert Douglas, 

 of Waukegan, 111., writes me as follows: ^^ Juniper us 

 Virginiana grown from seeds from southern Illinois 

 and Tennessee, is not only not so hardy as the same 

 tree from oui* northern Illinois and Wisconsin seeds, 

 but it is quite tender. My experience in this direc- 

 tion leads me to believe that this is the case with all 

 trees. We planted side by side black walnuts col- 

 lected from trees here and from trees in southern 

 Illinois. The trees from the latter nuts made nearly 

 double the growth of ours under the same conditions, 

 but the next spring they were found to be killed to 

 the ground, while ours were not injured even in the 

 terminal bud.* Pseudotsuga Douglasii from Colo- 

 rado seeds is hardy here, also in Massachusetts and 

 on the western prairies. The seeds of the same tree 

 from California, Oregon and Washington produce 

 tender trees, which will stand neither our climate 

 nor that of Massachusetts, as has been proved by 

 Professor Sargent and several others." The Phil- 

 adelphia Press for July 6 states that ' ' at the late 

 nurserymen's convention Robert Douglas said that 

 trees from seed of Pinus ponderosn brought from the 

 Pacific slope are not hardy, while "the same from seed 



♦This experience with the walnut properly falls under the next division of our 

 subject, as the variation in habit of the trees appears to be the cause of differ- 

 ences in hardiness. 



