260 MR. PERCY GROOM ON BUD-PROTECTION IN DICOTYLEDONS. 
to two or three pairs of leaves and their stipules. Тһе leaves and stipules arise (almost) 
at the same time, so that I failed to find leaves without stipules. At first there is only 
a very insignificant sheath common to stipule and leaf, later it increases in size; but 
when the leaves are mature, one only sees slight indications of the fact that leaves and 
stipules originally formed a shallow sheath round the stem. 
The first trace of the glandular surface of the stipule is a tongue-like emergence 
which hangs down from the apex of the stipule on its inner side; this gland, in fact, 
looks just like the ineurved apex of the stipule (Pl. LX. figs. 12 and 13). Gradually the 
epidermis of the inner face of the stipule assumes the form of a secreting epithelium, 
the change travelling in a basipetal direction. The modifying epidermis is raised up 
here and there into lobes and ridges, which at first hang down over the growing-point 
and younger leaves. 
Gurdenia florida, Linn., has its leaves in opposite pairs, or, more rarely, in whorls of 
three. The stipule forms a continuous sheath surrounding the stem, and in the young 
bud it completely invests the younger leaves till forced open by their growth (Pl. LIX. 
fig. 14). Numerous villous colleters line the inner face of the leaf- and stipule-base. These 
colleters secrete the well-known Gardenia-resin, which is really a mixture of gummy 
mucilage and resin: this secretion has a disagreeable odour, and is used in India to 
protect objects from insects. These colleters also occur on the side of the calyx-base. 
Mode of Secretion.—Both the mucilage and the resin arise in the protoplasm of the 
secreting-cells. Very young secreting-cells are square in outline ; they possess a granular 
protoplasm and a good-sized nucleus. They soon elongate in a direction at right angles 
to the surface of the colleter. At this stage, sections cut in two per cent. solution 
of potassic nitrate showed the protoplasm slightly withdrawn from the walls of these 
cells. Adding iodiné solution. or potassic bichromate, small bubbles of mucilage (or 
mucigen) could be seen protruding from the surface of the protoplasm beneath the 
external and lateral cell-walls (РІ. LX. figs. 16, 17, 18). In the more central parts of the 
cytoplasm granules or globules of smaller size could be seen. Owing to the small size of 
the latter, I am unable to state whether they are proteid or mucilaginous in nature; 
but the appearances naturally suggest that they change into the mucilage drops found 
towards the outside of the protoplasm. Thus the mucilage arises in the form of 
droplets in the cytoplasm; the droplets are expelled through the lateral and external 
cellulose walls, where they fuse to form rod-like or plate-like masses, which in turn unite 
to form a subcuticular mass. The secretion ultimately invests the cells on all sides, 
except the inner side, and raises the cuticle to a considerable height (fig. 18). The 
protruding drops of mucilage within the cell, and the smaller central granules or 
globules, stain slightly differently from the mucilage which lies under the cuticle, even 
after the removal of the resin. This suggests that some change ensues as the drops pass 
through the cellulose wall or after their expulsion from the cell. Thus the mode of 
origin of the mucilage appears to resemble that described by Gardiner and Ito (15), 
as occurring in the hairs of the palee of Blechnum and Osmunda. Concerning the 
origin of the resin, I can only give the bare fact, as Hanstein originally gave it in other 
types, that resin occurs inside the secretory cells. 
