Anyhow, it is manifest that the phosphate of lime is a most powerful
stimulant. Even small doses are more or less poisonous, probably on the
same principle that raw meat and other nutritious substances, given in
excess, kill the leaves. Hence the conclusion, that the long continued
inflection of the tentacles over fragments of bone, enamel, and
dentine, is caused by the presence of phosphate of lime, and not of any
included animal matter, is no doubt correct.
Gelatine. I used pure gelatine in thin sheets given [page 111] me by
Prof. Hoffmann. For comparison, squares of the same size as those
placed on the leaves were left close by on wet moss. These soon
swelled, but retained their angles for three days; after five days they
formed rounded, softened masses, but even on the eighth day a trace of
gelatine could still be detected. Other squares were immersed in water,
and these, though much swollen, retained their angles for six days.
Squares of 1/10 of an inch (2.54 mm.), just moistened with water, were
placed on two leaves; and after two or three days nothing was left on
them but some acid viscid fluid, which in this and other cases never
showed any tendency to regelatinise; so that the secretion must act on
the gelatine differently to what water does, and apparently in the same
manner as gastric juice.* Four squares of the same size as before were
then soaked for three days in water, and placed on large leaves; the
gelatine was liquefied and rendered acid in two days, but did not
excite much inflection. The leaves began to re-expand after four or
five days, much viscid fluid being left on their discs, as if but
little had been absorbed. One of these leaves, as soon as it
re-expanded, caught a small fly, and after 24 hrs. was closely
inflected, showing how much more potent than gelatine is the animal
matter absorbed from an insect. Some larger pieces of gelatine, soaked
for five days in water, were next placed on three leaves, but these did
not become much inflected until the third day; nor was the gelatine
completely liquefied until the fourth day. On this day one leaf began
to re-expand; the second on the fifth; and third on the sixth. These
several facts
* Dr. Lauder Brunton, Handbook for the Phys. Laboratory, 1873, pp.
477, 487; Schiff, Lecons phys. de la Digestion, 1867, p. 249. [page
112]
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