elation to common broccoli, as Brussel-sprouts do to common
cabbages; it suddenly appeared in a bed of common broccoli, and was
found faithfully to transmit its newly-acquired and remarkable
characters.

The principal kinds of cabbage existed at least as early as the
sixteenth century,[585] so that numerous modifications of structure
have been inherited for a long period. This fact is the more remarkable
as great care must be taken to prevent the crossing of the different
kinds. To give one proof of this: I raised 233 seedlings from cabbages
of different kinds, which had purposely been planted near each other,
and of the seedlings no less than 155 were plainly deteriorated and
mongrelized; nor were the remaining 78 all perfectly true. It may be
doubted whether many permanent varieties have been formed by
intentional or accidental crosses; for such crossed plants are found to
be very inconstant. One kind, however, called "Cottager's Kale," has
lately been produced by crossing common kale and Brussel-sprouts,
recrossed with purple broccoli,[586] and is said to be true, but plants
{325} raised by me were not nearly so constant in character as any
common cabbage.

Although most of the kinds keep true if carefully preserved from
crossing, yet the seed-beds must be yearly examined, and a few
seedlings are generally found false; but even in this case the force of
inheritance is shown, for, as Metzger has remarked[587] when speaking
of Brussel-sprouts, the variations generally keep to their "unter art,"
or main race. But in order that any kind may be truly propagated there
must be no great change in the conditions of life; thus cabbages will
not form heads in hot countries, and the same thing has been observed
with an English variety grown during an extremely warm and damp autumn
near Paris.[588] Extremely poor soil also affects the characters of
certain varieties.

Most authors believe that all the races are descended from the wild
cabbage found on the western shores of Europe; but Alph. De
Candolle[589] forcibly argues on historical and other grounds that it
is more probable that two or three closely allied forms, generally
ranked as distinct species, still living in the Mediterranean region,
are the parents, now all commingled together, of the various cultivated
kinds. In the same