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Selected Articles. 
The tree which affords the bark now under consideration, 
grows spontaneously on the Pitaya mountains, in the province 
of New Grenada. Its genus and species are not well de- 
termined. But as Peretti has ascertained that the bark con- 
tains neither quinine nor cinchonine ; the tree cannot be re- 
ferred to the genus Cinchona, especially, since a great number 
of plants that had been improperly placed in this genus, have 
been judiciously separated by Mr. Decandolle, and distributed 
in the new divisions he has established. Messrs. Brera and 
Guibourt, think that the pitaya belongs in all probability to 
the genus Exostema ; the last author has been influenced in 
his opinion, by the great resemblance between the words 
Pitaya and Piton, the latter of which is commonly given to 
the Exostema floribunda, piton or St. Lucia bark. But Folchi 
opposes to Guibourt's opinion the following argument, which 
he thinks has a considerable weight. 
It has been remarked that the trees affording bark, present 
a certain regularity as to natural localities ; thus, for instance, 
it is well known that the Luculia and Hymenodictyon, are in- 
digenous to the East Indies; that the Danais grows in southern 
Africa ; the Pinckneya, in Georgia and Florida ; the Remija, 
in Brazil, &c. and so it is with the whole geographical dis- 
tribution. Now the genus Exostema, and especially the first 
section, Pitonia, to which all the true Exostemas belong, is 
peculiar to the West India Islands, a country very different 
from that in which we are certain our pitaya grows naturally. 
Mr. Folchi is inclined to think that this tree belongs to the 
genus Buena, which is constantly met with, as well as the 
genus Cinchona, on the coast of Peru and New Grenada, with 
a single exception, however, that of the Buena hexandra, 
which grows in Brazil. 
Chemical Investigation. — The first experiments of Mr. Pe- 
retti were made with a view to ascertain whether the pitaya 
bark contained any of the vegetable alkalies of the cinchona ; 
but his experiments were negatived, but whilst he was dis- 
appointed in this respect, he had on another hand, the ad- 
vantage of ascertaining that it contained a peculiar alkaloid. 
