92 DROSERA ROTUNDIFOLIA. [Cuar. VI. 
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 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 ,!, 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 ab- 
sorbed 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 prove 
that gelatine is far from acting energetically on Drosera. 
In the last chapter it was shown that a solution of isin- 
glass of commerce, as thick as milk or cream, induces strong 
inflection, I therefore wished to compare its action with that 
of pure gelatine. Solutions of one part of both substances 
* Dr. Lauder Brunton, ‘Handbook for the Phys. Laboratory,’ 1873, pp- 
477, 487; Schiff, ‘ Leçons phys. de la Digestion,’ 1867, tom. ii. p. 249. 
