SIZE OF THE AGE CLASSES. 213 



It is obvious, that, for tlie shelter-wood sj'stem with natural 

 regeneration, the above allotment is only of an ideal character, 

 because the duration of regeneration is so uncertain. The 

 regeneration class, the oldest and youngest classes are subject 

 to modifications amongst themselves, so that they cannot 

 easily be separated the one from the other ; hence, they are 

 best thrown together. The important point in that case is, 

 that the middle-aged classes are of the proper size. The 

 allotment may then be represented as follows : — 



Example : — 



('.,= ' X II = 200 acres. 



