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, 144) 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, x 6; 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

7.5

verse section (fig. 143) the young leaf-blades are protected by three stipules, two belonging to the outer leaf, the third to that next following.

Here, therefore, though the main protection is afforded by stipules, the leaf-stalk and leaf-blade of an older leaf sometimes take a part in it.

FIG. 149.-Shows uppermost leaf with its stipules protecting the terminal bud in autumn; b, bud in the axil of the next lower leaf which has fallen. FIG. 150.-Second stage, shows aborted leaf, a, the stipules of which protect the winter-bud.

FIG. 151.-Side view of same.

The second pair of stipules (fig. 147) of the more typical lateral buds are free, unequal, imbricate, and completely cover their own leaf and two out of the three sides of the more or less trigonous bud. The outer stipule

of this second pair is ovate, more or less exposed along the middle and at the apex, which is curved, the exposed portions being more coriaceous than the rest. The inner of the two is half-ovate, pale green, and membranous. Both are traversed longitudinally by slender parallel

TERMINAL BUD OF MAGNOLIA UMBRELLA, x 12.

FIG. 152.-Uppermost leaf still present.

FIG. 153.-Uppermost leaf has fallen, leaving only a pedestal, p; its stipules remain to protect the winter-bud.

nerves.

The leaf in connection with the second pair is lanceolate-oblong, acute, serrate, glandular, and plicate along the course of the ascending nerves.

It is more

or less folded over the younger members of the bud. All the leaves and stipules are glued together by a viscid, resinous, fragrant gum, secreted by glands.

The third pair of stipules (fig. 148) are slightly un

equal, narrowly ovate or lanceolate, membranous, and more faintly nerved than the previous pair. The outer stipule envelops about two-thirds of the bud, including its fellow-stipule and the leaf. The latter is ovateelliptic and folded over the younger members of the bud as a rule. The fourth pair of stipules and their leaf (fig. 148) are sometimes very similar to the preceding set, sometimes much smaller. This difference is apparently due to the relative vigour of the axis bearing them.

A somewhat similar case is afforded by certain species of Magnolia. In Magnolia Yulan the stipules of the uppermost leaf protect the young bud in autumn (fig. 149), but when it drops the stipules fall with it. This leaves a small undeveloped leaf-blade (fig. 150, a), which soon perishes. The stipules belonging to it, however, remain, and form a silky case, which protects the bud.

The leaf-blade corresponding to a, therefore, is useless and wasted.

Another species (Magnolia Umbrella) (figs. 152, 153) avoids this waste of power and material. When the last leaf of the year dies and drops off, the stipules belonging to it remain and protect the bud (fig. 153). Under these circumstances the leaf corresponding to a, which in Magnolia Yulan perishes uselessly, in Magnolia Umbrella is still retained, and develops into the first leaf of the following year. In M. Soulangiana, a garden hybrid, there is a similar arrangement.