verticil and crossed in the two
successive ones. The stem is four-angled, each angle having a nerve.
Each of these nerves, springing from the origin of a branch in one
whorl, terminates in the interval which separates the point of origin of
the two branches in the whorl next above it. In the deformed stem one of
the nerves corresponds to the insertion of a branch, its neighbour is in
the adjoining vacant space; hence it results that four nerves correspond
to two branches and to two consecutive interspaces, and hence the
analogy between a single normal internode provided with its two branches
and its four nerves. What confirms this inference is that the nerve,
which begins at the point of origin of a branch, after making one spiral
turn round the stem, terminates in the interval that separates the two
following branches, just as in a branch of the normal stem it ends in
the upper whorl between the two next branches. The torsion, then, in
this _Galium_ caused the separation of the two opposite branches of the
same verticil, and placed them one above another, and this being
reproduced in all the whorls, all the branches come to be arranged on
the same longitudinal line. The leaves are susceptible of the same
explanation; they are inserted in groups of three or four in one arc
round the origin of each branch. In the malformation each series or
group of four leaves, with its central branch, is equivalent to half a
whorl of the natural plant with its axillary branch. In other words, the
malformation consists in a torsion of the stem, which separates each
whorl into two distinct halves; these half-whorls, with their axillary
branches, are placed on a single longitudinal series one above another.
This case is quoted at some length, as it is an admirable example of a
very common form of malformation in these plants.

In some parts of Holland where madder is cultivated a similar
deformation is particularly frequent. The leaves, however, are not
always grouped in the way in which they were described by M. Duchartre,
but more commonly form a single continuous line; when arranged in
leaf-whorls it generally happens that some of the leaves are turned
downwards, while others are erect. It has been said that this condition
occurs particularly frequently in plants growing in damp places. It is
certainly true that spiral torsion of the stem is specially frequent in
the species of _Equisetum_, most of which grow in such spots. In these
p