2 j6 Ewart. — On the Leaf-glands of 
most of them, however, have been confirmed on material from 
other sources. 
I made use of young vigorous shoots of Ipomoea panicidata. 
The younger leaves were detached and the glandular region 
was cut away from the rest of the blade and petiole and put 
at once into absolute alcohol. The axillary buds which had 
been carefully left untouched on the stem were removed in 
succession at various stages. 
Description of Gland. The under side of the leaf-blade is 
traversed by five prominent veins which diverge from the top 
of the petiole, the midrib passing up the centre of the leaf, 
with two smaller veins on either side. The tissue covering 
these smaller veins expands at their point of union on the 
under surface of the leaf into a projecting cushion (c. Fig. i) 
which overhangs the glandular region. Below the cushion is 
the slight concavity holding the fluid secretion, and from its 
centre, in the plane passing midway between the two veins, 
rises the papilla with its crater-like mouth. The papilla has 
a darker colour than the rest of the leaf, owing to a purple 
pigment in its sub-epidermal cells ; it is elongated more or 
less horizontally, i.e. in a direction at right angles to the long 
axis of the petiole (p. Fig. i). The duct which traverses it is 
short and straight, and passes horizontally inwards (perpen- 
dicular to the surface of the petiole), to widen out in the gland 
below. A tangential section of the papilla presents the 
appearance shown in Fig. 4. Occasionally, instead of forming 
a long straight narrow slit ( d ), it has the appearance of a Y in 
transverse section. Its lining-membrane is strongly cuticu- 
larized, and the cells immediately surrounding it are marked 
off from the neighbouring parenchyma by their smaller size 
and more compact setting (Fig. 4 p). It is the multiplication 
of these smaller cells which gives rise to the papilla on the 
surface, i.e. to the tiny perforated cone. The cushion of tissue 
overhanging the gland serves to deepen the depression in 
which it lies, and so allows a considerable amount of secretion 
to accumulate there before falling. 
The internal orifice of the duct widens out into the lumen 
