in a drop. It is formed by papillary outgrowths of the epidermis.

The buds of Chilocarpus look as if they were covered by red sealing-wax (16).

A

B

FIGS. 140, 141.-DEVELOPMENT OF HAIRS IN PLANE

(Platanus acerifolia).

An epidermal cell divides into two unequal parts by an oblique wall. The upper grows out into a 2-4-celled hair, the apical cell of which becomes a spherical gland-cell; a lateral cell grows out obliquely into a long, pointed, hair-like structure. The lower figure shows the development, the upper the perfect form of the hairs.

The case of Tabernæmontana (1, 351) is especially interesting. The buds of this plant are covered with a

gum which does not completely harden, but remains in a semi-fluid condition; and as the leaves previously covered up grow and expand, the gum remains attached to their edges, and stretches as a thin film between them. Thus the next youngest leaves are for a certain time enclosed in a small four-sided chamber, two opposide sides of which are formed by two leaves, and the other two opposite sides by a thin film of gum. The gum is eventually ruptured and the same process is repeated.

Glands are present in the axils of the leaves in the great majority of Crucifers (Norman says in nine-tenths), in most Lythrariece, and in many others.

The connection of these glands with the protection of the young and highly delicate leaf is further shown by their very early development. In fact, in some species there is a stage in which the glands are actually larger than the rudiment of the leaf itself. They are, however, often very transitory.

97

CHAPTER V

ON THE STRUCTURE OF BUDS

HAVING thus glanced at the various ways in which buds are protected by other and older structures, let us now see how they behave when they are, so to say, thrown on their own resources. In doing so I will, as far as possible, take in illustration our familiar forest trees and other common plants.

It is in some respects difficult to draw a hard-andfast line between the buds now to be considered and those described in the last chapter.

In the Whitebeam (Pyrus Aria) (fig. 125, p. 82), for instance, the pedestal of the last leaf of the previous year is persistent, and, no doubt, of some use to the very young bud; but I class it here because in the main the shelter is due to the outer, modified stipules belonging to the bud itself.

It is remarkable how many devices Nature has adopted, and how much even nearly allied groups, such, for instance, as the Willows and Poplars, differ from one another.

It is, indeed, a very general, though not invariable, rule that the outer envelopes of winter-buds are formed

H

of brown, more or less leathery scales; but as we shall see, these scales represent very different organs.

If we examine the bud of an Alder (Alnus glutinosa) (figs. 142, 143, 141) in winter, we shall find that it is

FIG. 142.-Portion of shoot, showing two lateral buds in winter; Sc, scar of fallen stipule, leaving L, the corresponding leaf, exposed; St, the stipule of the next leaf; the upper bud shows only one stipule, St, but none have fallen in this instance, which is the more common case. Nat. size.

FIG. 143.-Transverse section of bud in winter, x6; A, A, first or outermost pair of stipules, belonging to the leaf immediately beneath them; B, B, second pair of stipules with their leaf; c, c, third pair; the fourth leaf, D, D, and stipules occupy the centre; Ax, axis.

protected by three, or sometimes four, purplish brown, leathery scales. The lateral buds sit on gradually elon

gating pedestals. If there are three scales, these are stipules. When four are present, one will be found to have at the end a few finger-like processes (fig. 142, L), the rudiment of a leaf-blade. At the base will be found the more or less evident scars left by the two stipules.

FIG. 144.-Portion of shoot bearing a lateral bud; o.s., outer scale; s.s., second scalethat is, the outer one of a pair of stipules.

FIG. 145.-Outer scale of winter-bud.

FIG. 146.-0.S., outer, and i.s., inner stipule of the first distinct pair; 7, their leaf, flattened out like the stipules.

FIG. 147.-0.st., outer, and i.st., inner stipule of the second distinct pair; 7, their leaf. FIG. 148.-0.st., outer, and i.st., inner stipule of the third distinct pair; 7, their leaf.

In this case, therefore, the last leaf of autumn is small, and sooner or later falls off; but, in connection with the stipules of the next leaf, it often assists in protecting the bud through the winter. It often, however, becomes detached, and in such buds as shown in the trans