( 317 ) 
of the teeth and the smaller leafteeth, which are turned inwards, 
had at this stage already lost most of their contents and had become 
brown. In the younger leaves they produced much mucilage and 
the youngest leaflets of the bud were completely enveloped in it. 
In addition to these large glands every leaf bears, especially on its 
upper surface, a large number of smaller mucilage-glands, which 
too, are stalked and are compound and more or less spherical; 
furthermore the leaf is also covered with long thick-walled bristles. 
Not only the leaves, but also the stipules bear in the bud numerous 
mucilage-glands of both kinds: larger ones at the margin in a pretty 
close row. between the hairs and smaller ones on the leaf surface, 
especially on the lower portion of the stipule. In the very youngest 
stipules and leaves these small spherical glands cannot yet be observed; 
they only appear when the large glands at the margin and at the 
apex have already lost their contents; as in Kerria japonica the 
apex and the margin of the leaves of Corylus show a growth in 
advance of that of the rest of the leaf. 
In the moist atmosphere under the glass bell-jar the outermost 
leaflets, which are most advanced in development, become covered 
on their upper surface with numerous clear drops of fluid. Often 
the hairs at the edge of the leaflets are covered with clear droplets. 
This fluid is secreted by the glands of the leaf surface, which origi¬ 
nally secreted mucilage, but now secrete water containing but little 
mucilage. On the first day there is seldom any real dripping, but 
the secretion of water may nevertheless be relatively important. 
Ulmus campestris 1 ). 
In Ulmus campestris the leaves are folded up in the bud round 
the middle vein and are placed to the left and right of the central axis. 
When, on the 2 nd of May, a cut branch was placed under the 
glass bell-jar, the lowest leaf of most of the buds had unfolded itself 
and was beginning to turn itself outwards; the next leaf was still 
erect but the halves of the leaf had begun to separate a little; the 
higher leaves were still all folded up and enclosed by the stipules. 
The young leaves bear long, pointed, unicellular hairs with rounded 
base, which are bent parallel to the leaf-surface; in addition these 
leaves are covered especially on the upper surface, with mucilage 
glands (Trichomzotten) which consist of 4 cells, viz. of a short basal 
cell, a cylindrical stalk-cell and two gland-cells placed one above 
the other, of which the upper one is hemi-spherical; the glands 
^ Ver g- Rhnke lx.’ p. 156. 
Proceedings Royal Acad. Amsterdam. Vol. XII. 
22 
