glandular hairs are far more simple in structure than the so-called
tentacles of the preceding genera, and they do not differ essentially
from those borne by innumerable other plants. The flower-peduncles bear
similar glands. The most singular character about the leaves is that
the apex is enlarged into a little knob, covered with glands, and about
a third broader than the adjoining part of the attenuated leaf. In two
places dead flies adhered to the glands. As no instance is known of
unicellular structures having any power of movement,* Byblis, no doubt,
catches insects solely by the aid of its viscid secretion. These
probably sink down besmeared with the secretion and rest on the small
sessile glands, which, if we may judge by the analogy of Drosophyllum,
then pour forth their secretion and afterwards absorb the digested
matter.
Supplementary Observations on the Power of Absorption by the Glandular
Hairs of other Plants. A few observations on this subject may be here
conveniently introduced. As the glands of many, probably of all,
* Sachs, Traite de Bot., 3rd edit. 1874, p. 1026. [page 345]
the species of Droseraceae absorb fluids or at least allow them readily
to enter,* it seemed desirable to ascertain how far the glands of other
plants which are not specially adapted for capturing insects, had the
same power. Plants were chosen for trial at hazard, with the exception
of two species of saxifrage, which were selected from belonging to a
family allied to the Droseraceae. Most of the experiments were made by
immersing the glands either in an infusion of raw meat or more commonly
in a solution of carbonate of ammonia, as this latter substance acts so
powerfully and rapidly on protoplasm. It seemed also particularly
desirable to ascertain whether ammonia was absorbed, as a small amount
is contained in rain-water. With the Droseraceae the secretion of a
viscid fluid by the glands does not prevent their absorbing; so that
the glands of other plants might excrete superfluous matter, or secrete
an odoriferous fluid as a protection against the attacks of insects, or
for any other purpose, and yet have the power of absorbing. I regret
that in the following cases I did not try whether the secretion could
digest or render soluble animal substances, but such experiments would
have been difficult on account of the small size of the glands and the
small amount of secretion. We shall see in the next chapter that the
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