mention this plant because it has
varied in certain characters, namely, in the texture and quality of the
leaves, fitting them to serve as food for the domesticated silkworm, in
a manner not observed with other plants; but this has arisen simply
from such variations in the mulberry having been attended to, selected,
and rendered more or less constant. M. de Quatrefages[623] briefly
describes six kinds cultivated in one valley in France: of these the
_amourouso_ produces excellent leaves, but is rapidly being abandoned
because it produces much fruit mingled with the leaves: the _antofino_
yields deeply cut leaves of the finest quality, but not in great
quantity: the _claro_ is much sought for because the leaves can be
easily collected: lastly, the _roso_ bears strong hardy leaves,
produced in large quantity, but with the one inconvenience, that they
are best adapted for the worms after their fourth moult. MM.
Jacquemet-Bonnefont, of Lyon, however, remark in their catalogue (1862)
that two sub-varieties have been confounded under the name of the
_roso,_ one having leaves too thick for the caterpillars, the other
being valuable because the leaves can easily be gathered from the
branches without the bark being torn.

In India the mulberry has also given rise to many varieties. The Indian
form is thought by many botanists to be a distinct species; but as
Royle remarks,[624] "so many varieties have been produced by
cultivation that it is difficult to ascertain whether they all belong
to one species;" they are, as he adds, nearly as numerous as those of
the silkworm.

_The Orange Group._--We here meet with great confusion in the specific
distinction and parentage of the several kinds. Gallesio,[625] who
almost devoted his life-time to the subject, considers that there are
four species, namely, sweet and bitter oranges, lemons, and citrons,
each of which has given rise to whole groups of varieties, monsters,
and supposed hybrids. One high authority[626] believes that these four
reputed species are all {335} varieties of the wild _Citrus medica_,
but that the shaddock (_Citrus decumana_), which is not known in a wild
state, is a distinct species; though its distinctness is doubted by
another writer "of great authority on such matters," namely, Dr.
Buchanan Hamilton. Alph. De Candolle,[627] o