326 ON THE CUTICLE OF PLANTS. 
form a thick stratum, while in the thin leaves of a Dianthus 
they form a thin stratum, and that in the thick leaves the 
cuticle generally gives rise to attenuated lamine, which make 
their way between the epidermal cells. If then, the obser- 
vations adduced, prove that the cuticle of coriaceous leaves 
is no distinct membrane; but arises from the union of the 
primary cellular membrane with a greater or less quantity of 
secondary layers of the epidermal cells, we are compelled to 
allow the same mode of development in the thin cuticle of 
herbaceous leaves. 
In all the forms hitherto examined, the cuticle was situated 
on the outer side of the epidermal cells, or rather was formed 
through incrassation of their walls. The cuticle of the leaves 
of Billbergia zebrina and Bromelia ananas is an exception 
to this, for in these cases the outer wall of the epidermal 
cells exhibits only a moderate thickness, while that of the 
inner wall is considerable, and at the same time the sub- 
jacent layer of cells possess thickened walls on their outer- 
side, so that the cuticle thus formed lies between two rows 
of cellular cavities. ae 
The union of the cuticle with the other membranes of the 
epidermal cells is in leaves and stems very intimate. The 
case is quite different with the cuticle of the stigmatic papille 
of many plants, since it possesses a greater compass than the 
cells inclosed by it, consisting of secondary membrane, as is 
very beautifully seen in Convallaria multiflora, Papaver 
orientale and Glaucium luteum. According to the assertion 
of Hartig (neue Theorie der Befrucht. der Pf. S. 23) in this- 
case the cuticle does not clothe the whole hair; but extends — 
only to the point where the base of one hair is joined to — 
that of another, over which it passes without interruption, 
and thus forms a common envelope. I am unable, how- 
ever, to confirm this, though in the above named plants 
especially in Papaver orientale I have separated the papille 
from one another, and seen merely the membrane distinctly | 
surrounding the whole hair under the form of a closed cell. 
The interval between the outer thin membrane which i$ — 
