190 RUBIACEM. 
the alkaloids contain 41 per cent. of quinine in the total 
alkaloids, and the Ledger hybrid 58 per cent. . 
Ledgers and Succirubras do not much increase in alkaloidal 
value after 6 years of age, and therefore should not be barked 
when young. The Officinalis, being of slower growth, does 
not mature or yield the full amount of alkaloid, until the 
trees are at least 7 years old. The faster-growing trees appear 
to begin to degenerate after 15 years, and the Officinalis after 
20 years. a 
~ The north or shaded side of a tree has a richer bark 
than that on the south side—a fact which explains the success 
of the mossing-system, where the bark is entirely protected 
from the light and heat of the sun’s rays, and a larger yield of 
alkaloids thereby encouraged. The renewal of most barks 
under moss, or a similar covering, has a tendency to increase 
the amount of quinine at the expense of the cinchonidine; 
(C. micrantha, &c.), where no quinine or cinchonidine are 
found in natural bark, cinchonidine is formed at the expense of 
_ the cinchonine, which is always present in these barks in large 
quantity. 
se 
A large number of experiments have been made in manur-— 
the bark of young trees more quickly than that of older 
ones; but, on the other hand, old trees of twelve years and 
upwards are greatly improved by manure when it is allowed 
longer time to work, about two years or more. 
: Some analyses of frost-bitten barks show that there is very ‘ 
bark analysed before the frost. It was formerly supposed 
that frost-bitten barks were Worthlesse Cicdeicies 
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