ttle
plants the internodes are very short and the stems are few in number, and
attain to a length of only 9-10 inches. In course of growth they diverge
from one another, and come to lie prostrate on the ground (Pl. II., 2).
Curiously enough, although the whole plant is dwarfed in other respects,
this does not seem to affect the size of the flower, which is that of a
normal sweet pea. Another though less-known variety is the "Bush" sweet
pea. Its name is derived from its habit of growth. The numerous stems do
not diverge from one another, but all grow up side by side, giving the
plant the appearance of a compact bush (Pl. II., 1). Under ordinary
conditions it attains a height of 3-1/2-4 feet. A number of crosses were
made between the Bush and Cupid varieties, with the somewhat unexpected
result that in every instance the F_1 plants showed complete reversion to
the size and habit of the ordinary tall sweet pea (Pl. II., 3), which is
the form of the wild plant as it occurs in Sicily to-day. The F_2
generation from these reversionary talls consisted of four different types,
viz. {64} talls, bushes, Cupids of the procumbent type like the original
Cupid parent, and Cupids with the compact upright Bush habit (Pl. II., 4).
These four types appeared in the ratio 9 : 3 : 3 : 1, and this, of course,
provided the clue to the nature of the case. The characters concerned are
(1) long internode of stem between the leaves which is dominant to short
internode, and (2) the creeping procumbent habit which is dominant to the
erect bush-like habit. Of these characters length of internode was carried
by the Bush, and the procumbent habit by the original Cupid parent. The
bringing of them together by the cross resulted in a procumbent plant with
long internodes. This is the ordinary tall sweet pea of the wild Sicilian
type, reversion here, again, being due to the bringing together of two
complementary factors which had somehow become separated in the course of
evolution.

To this interpretation it may be objected that the ordinary sweet pea is a
plant of upright habit. This, however, is not true. It only appears so
because the conventional way of growing it is to train it up sticks. In
reality it is of procumbent habit, with divergent stems like the ordinary
Cupid, a fact which can easily be observed by anyone who will watch them
grow without the artificial aid of prepared supports.

[Illustration: PLATE II.

1, Bush Sweet Pea; 2, Cupid Swe