110 THE ESSEX NATURALIST.
Bolivia in the south to Colombia in the north. But ecologica
study in the field and systematic investigation in the herbarium
combine in suggesting that this genus resembles the equally
natural genera Rosa and Rubus here, and Crataegus in North
America, in exhibiting a protean diversity of distinguishable
forms, the status of which is often doubtful. If field botanists
be right, there may be anything up to eighty distinct species; if
the judgment of cabinet students be sound, there may be less
than half that number. On the other hand, the economic botanist,
guided as he must be by the expert knowledge of the chemist,
knows that whatever the number of natural species may be,
practical interest, prior to 1820, was confined to four commercial
kinds of Cinchona Bark, "pale," "red," "yellow," and "grey,"
obtained from the southern Viceroyalty, which retained the name
Peru after the separation from it in 1718 of the northern Vice-
royalty of New Granada. After 1820, again, whatever the
number of species involved, this practical interest extended only
to two additional commercial kinds, "soft," and "hard." The
factor which limited attention to the four kinds exploited prior
to 1820 was the presence in these barks of a percentage of the
alkaloids which render them remedial against malaria sufficient
to make their exploitation worth while; after 1820, exploitation
was governed by the presence in the bark of a suitable proportion
of one particular anti-malarial alkaloid. One sequel of this
modification of economic outlook was to render the exploitation
of "grey" bark so unprofitable that after 1820 only five sorts
were used. To-day only one sort can be cultivated by those
who wish to avoid financial loss.
There is nothing to suggest that between 1643, when Cardinal
de Lugo undertook the distribution of quina-quina at Rome,
and 1739, when Condamine investigated the exploitation of
quina-quina in Loja, more than one kind of bark was intention-
ally shipped to Spain, But it is on record that, in 1735, Ulloa
warned the Peruvian authorities that, unless they took steps
to conserve the forest resources of Loja they would find that
supplies of the bark then collected must become exhausted, and
it is clear that, although this warning was unheeded, exploiters
were already seeking for substitutes for the bark to which their
attention had so far been confined. We know that in 1738
Condamine was shown a "red quina-quina," which he was