262 MR. PERCY GROOM ON BUD-PROTECTION IN DICOTYLEDONS. 
bundles run close up to the villi, so that the “nerve-parenchyma” and conducting 
parenehyma of the colleters are directly continuous. Many laticiferous tubes traverse 
the leaf-parenchyma and send branches into the colleters (fig. 23). 
Judging from the alcohol material at my disposal, the secretion seems to be of a 
resin-mucilage nature rather than a “ wax-like substance." The papillose epidermis on 
the upper face of the “ ledges " aids in the process of secretion. 
Alstonia scholarius, R. Br., in its mode of bud-protection reminds one of Taber- 
nemontana. Examining with the naked eye, а circlet of leaves is seen at the apex of 
the stem. From the base of each leaf a small tooth-like axillary process projects and 
lies above the younger leaves; this tooth-like process is obviously homologous with 
the ledge-like process of Tubermemontana, and both may be described as axillary 
stipules. 
Allamanda sp.—The leaves are stalked and exstipulate, and according to the species 
are arranged in whorls of two, three, or four leaves. On the inner face of the “ base " 
of each leaf of the calyx-lobes is a row of about five villi: these villi cover the bud 
with a gummy mucilage and resin secretion. 
Structure of the Villi.—Yhe villi are normal in structure, but it may be mentioned 
that laticiferous tubes penetrate them and frequently ascend to the secreting cells even 
(fig. 24). The secreting-cells resemble some described by Hanstein, so they may be 
described more in detail. In a mature secreting-cell the general protoplasm is very 
granular and the nucleus lies in the middle of the cell. Typically a large tannin- 
globule rests in the inner (basal) part of the cell, or sometimes there are several similar 
globules. On removing the tannin it is seen that it merely soaked a viscous substance : 
the latter stains pink with Hanstein’s reagent, and is what Hanstein called “amyloid 
"Substance" (probably a mucilaginous substance). Outside the cells the secretion first 
appears in the intercellular spaces between the upper ends of the secreting-cells, rather 
than outside their outer walls. As the secretion increases in quantity it penetrates 
deeper between the cells and forms a sort of honeycomb structure. Some of the secre- 
tion is visible outside the cuticle before the rupture of the latter; so some of the 
secretion must pass through the cuticle. It was this sort of appearance which led 
Hanstein to suppose that two cuticles might be formed. Often in older stages it is 
visible, so one cannot resist the conclusion that the secretion may dissolve the 
cuticle. 
Landolphia sp.—We might anticipate that the long “feelers " of this climbing plant, 
with their tiny leaves and elongated internodes, would display a complete arrangement 
for protecting the young leaves; and the colleters do appear to secrete for a longer 
period than on plants not possessing those long sunlight-bathed “ feelers.” 
Nerium oleander has colleters and woolly hairs. 
ASCLEPIADEA. 
Asclepias curassavica.—Hanstein figured and described the colleters which occur on 
the leaf-base. It may be added that villi also occur on the inner face of the calyx-base. 
Ceropegia stapeliaformis.—At the base of each small, triangular, succulent leaf is a 
