and another cube on the glands of a sepal; but they were not excited to
increased secretion, and the albumen after two days was not in the
least softened. Hence these glands apparently differ greatly in
function from those on the leaves.]
From the foregoing observations on Pinguicula lusitanica we see that
the naturally much incurved margins of the leaves are excited to curve
still farther inwards by contact with organic and inorganic bodies;
that albumen, cabbage seeds, bits of spinach leaves, and fragments of
glass, cause the glands to secrete more freely; that albumen is
dissolved by the secretion, and cabbage seeds killed by it; and lastly
that matter is absorbed by the glands from the insects which are caught
in large numbers by the viscid secretion. The glands on the
flower-peduncles seem to have no such power. This species differs from
Pinguicula vulgarisand grandiflora in the margins of the leaves, when
excited by organic bodies, being inflected to a greater degree, and in
the inflection lasting for a longer time. The glands, also, seem to be
more easily excited to increased secretion by bodies not yielding
soluble nitrogenous matter. In other respects, as far as my
observations serve, all three species agree in their functional powers.
[page 395]
CHAPTER XVII.
UTRICULARIA.
Utricularia neglecta Structure of the bladder The uses of the several
parts Number of imprisoned animals Manner of capture The bladders
cannot digest animal matter, but absorb the products of its
decay Experiments on the absorption of certain fluids by the quadrifid
processes Absorption by the glands Summary of the observation on
absorption Development of the bladders Utricularia
vulgaris Utricularia minor Utricularia clandestina.
I was led to investigate the habits and structure of the species of
this genus partly from their belonging to the same natural family as
340