XX.] CLIMATE AS AFFECTING LONGEVITY. 337 



11. Cultural causes. 



4. Lack of adaptation of varieties to conditions. 



5. Forceful methods of cultivation. 



6. Lack of fertility, and neglect. 



7. Methods of propagation, 



8. Pruning. 



1. Change in climate. — It is asserted that climates 

 are becoming more severe, and that varieties which 

 were considered hardy fifty years ago often perish 

 now. Before we can reason definitely upon this 

 point, we must have proof that climate is becoming 

 more severe, yet I do not know that such proofs ex- 

 ist. I had thought of comparing old meteorological 

 records with recent ones in various states, but I find 

 that no adequate studies or records of climate, ex- 

 tending through a series of years, have been made. 

 There are abundant records of temperature, but 

 climate means more than relative heat. It comprises 

 humidity of atmosphere, character, frequency and di- 

 rection of winds, alternations of variations, progres- 

 sion of seasons, relative cloudiness, and many other 

 conditions. Recollections of climate are peculiarly 

 unreliable and vague, and many of the definite state- 

 ments concerning changes in climate are founded upon 

 assumptions. The only well -authenticated general 

 fact concerning recent changes in climate appears to 

 be the observation that severe winds are more fre- 

 quent in deforested areas than in forest regions; — the 

 country is bleaker. But the relations of this bleak- 

 ness to plant -life have not been carefully studied. 

 There are evidently recurring cycles of climatic dif- 

 ferences, and it is probably these more or less marked 

 periodical changes which people have confounded 

 22 suR. 



