round the margins of the discs were a little inflected, and the
secretion collected on the disc was acid, but the exterior tentacles
were not affected. One leaf began to re-expand on the fourth day, and
all were fully re-expanded on the sixth. The glands which had been in
contact with the mucin were a little darkened. We may therefore
conclude that a small amount of some impurity of a moderately exciting
nature had been absorbed. That the mucin employed by me did contain
some soluble matter was proved by Dr. Sanderson, who on subjecting it
to artificial gastric juice found that in 1 hr. some was dissolved, but
only in the proportion of 23 to 100 of fibrin during the same time. The
cubes, though perhaps rather softer than those left in water for the
same time, retained their angles as sharp as ever. We may therefore
infer that the mucin itself was not dissolved or digested. Nor is it
digested by the gastric juice of living animals, and according to
Schiff* it is a layer of this substance which protects the coats of the
stomach from being corroded during digestion.
Pepsin. My experiments are hardly worth giving, as it is scarcely
possible to prepare pepsin free from other albuminoids; but I was
curious to ascertain, as far as that was possible, whether the ferment
of the secretion of Drosera would act on the ferment of the gastric
juice of animals. I first used the common pepsin sold for medicinal
purposes, and afterwards some which was much purer, prepared for me by
Dr. Moore. Five leaves to which a considerable quantity of the former
was given remained inflected for five days; four of them then died,
apparently from too great stimulation. I then tried Dr. Moore s pepsin,
making it into a paste with water, and placing such small particles on
the discs of five leaves that all would have been quickly dissolved had
it been meat or albumen. The leaves were soon inflected; two of them
began to re-expand after only 20 hrs., and the other three were almost
completely re-expanded after 44 hrs. Some of the glands which had been
in contact with the particles of pepsin, or with the acid secretion
surrounding them, were singularly pale, whereas others were singularly
dark-coloured. Some of the secretion was scraped off and examined under
a high power; and it abounded with granules undistinguishable from
those of pepsin left in water for the same length of time. We may
therefore infer, as highly probable (remembering what small quantities
were given), that the ferment of Drosera does not act on or digest
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