36 
NATURAL HISTORY OF THE CINCHONAS. 
constitute the flat cinchona, or, as it is called, tabla or 
plancha, must necessarily undergo a certain degree of pres- 
sure during the process of desiccation, without which it 
would become mis-shapen, or take a cylindrical form as in 
the preceding case. To effect this, after first exposing the 
pieces of bark to the sun, they are placed one on the other 
in crossed squares, in a similar manner to that practised in 
timber-yards in the arrangement of the planks of wood, and 
on the top of this pile a heavy weight is placed. This pro- 
cess is repeated for several days until the bark is completely 
dried. 
The above process is that commonly adopted in preparing 
the cinchonas ; but it will be easily comprehended that this 
must vary, in some degree, according to the locality, or the 
nature of the tree operated upon. In many places the bark 
is not pressed at all, or but imperfectly so, and it is then 
generally out of form or slightly curled. The peridermis is 
often but partially removed, or simply scraped. Finally, 
whether it be accidental, or whether it be done with the 
view of augmenting the weight, there frequently remains a 
certain quantity of moisture in the bark which greatly dete- 
riorates it. It thus appears that cinchonas which would 
juices disappear by degrees from the bark, and that those barks only 
are efficacious which are taken from branches of moderate size, four 
times] as many trees were sacrificed as would have* been the case 
under other circumstances. It has been said, it is true, that the cas- 
carilleros climbed the trees to cut off the branches, taking care to leave 
the terminal branch; but those whom I have known have always can- 
didly confessed that they found the most simple method to be that of 
cutting the trees down, and this, I believe, has been the uniform prac- 
tice. Thousands of quintals of cinchona bark have been thus left to 
perish in the forests; and it has only been since the inutility of the 
practice has been proved by chemical analysis that it has been discon- 
tinued. It is not to be considered ; however, that the bark of old trees 
contains as much of the active principle as those which have only ar- 
rived at maturity. There are limits between which all are good; in- 
deed, none ought to be rejected. 
