points. Each point is tipped by a short, straight bristle; and slight
notches on the sides of the leaves bear similar bristles. On both
surfaces there are many small papillae, crowned with two hemispherical
cells in close contact. The plants float near the surface of the water,
and are quite destitute of roots, even during the earliest period of
growth.* They commonly inhabit, as more than one observer has remarked
to me, remarkably foul ditches.
The bladders offer the chief point of interest. There are often two or
three on the same divided leaf, generally near the base; though I have
seen a single one growing from the stem. They are supported on short
footstalks. When fully grown, they are nearly 1/10 of an inch (2.54
mm.) in length. They are translucent, of a green colour, and the walls
are formed of two layers of cells. The exterior cells are polygonal and
rather large; but at many of the points where the angles meet, there
are smaller rounded cells. These latter support short conical
projections, surmounted by two hemispherical cells in such close
apposition that they appear united; but they often separate a little
when immersed in certain fluids. The papillae thus formed are exactly
like those on the surfaces of the leaves. Those on the same bladder
vary much in size; and there are a few, especially on very young
bladders, which have an elliptical instead of a circular outline. The
two terminal cells are transparent, but must hold much matter in
solution, judging from the quantity coagulated by prolonged immersion
in alcohol or ether.
* I infer that this is the case from a drawing of a seedling given by
Dr. Warming in his paper, Bidrag til Kundskaben om Lentibulariaceae,
from the Videnskabelige Meddelelser, Copenhagen, 1874, Nos. 3-7, pp.
33-58.) [page 398]
The bladders are filled with water. They generally, but by no means
always, contain bubbles of air. According to the quantity of the
contained water and air, they vary much in thickness, but are always
somewhat compressed. At an early stage of growth, the flat or ventral
surface faces the axis or stem; but the footstalks must have some power
of movement; for in plants kept in my greenhouse the ventral surface
was generally turned either straight or obliquely downwards. The Rev.
H.M. Wilkinson examined
342