Part IV.] 
PRUNING AND THINNING. 
253 
next step taken by physiologists on this datum 
of Adanson’s will be, that all trees of thirty feet 
in diameter are 5150 years of age; and so, in 
proportion as the diameter of any tree exceeds 
or falls short of thirty feet, an age greater or 
less than 5150 years will be assigned to it : 
from which it would result that a tree must 
grow 174 years, nearly two centuries, before it 
would attain one foot in diameter. Lyell, 
speaking of a submarine forest at Bournmouth, 
in Hampshire, says: “ Seventy-six rings of an¬ 
nual growth were counted in a transverse sec¬ 
tion of one of the buried trees, which was four¬ 
teen inches in diameter.” This, though exceed¬ 
ingly slow growth, is about three times the 
growth allowed by Adanson. But were the 
rings perfect on each half diameter ? If not, 
the width of those wanting on the deficient half 
diameter must be added to the fourteen inches 
of growth. On the other hand, and in accord¬ 
ance with the rule above, we are told that De 
Candolle thinks that the Montezuma cypress 
(Taxodium sempervirens) at Mexico exceeds the 
age of the baobab,—exceeds these poor 5150 
years in age. And this opinion is quoted, with 
profound respect, by one of the most profound 
men of the day,—by Lyell. Did De Candolle 
