CHAP, ii.] The British Sylva 45 



in low-lying localities ; whilst with the free play of aerial currents in 

 Alpine tracts the fruits almost always dry up before they ripen V 



The crookedness of the stem may be due either to want of 

 depth of soil interfering with the normal development of the 

 strong tap-root, or else to the growth of the tree being stimu- 

 lated beyond normal and healthy limits, owing to the much 

 longer period of activity necessitated by our climate, in which 

 spring and autumn are gradual and prolonged stages between 

 the periods of foliation and defoliation. 



1 Lehrbuch der Baumkrankheiten, 2nd edit., 1889, p. 45. 



