they generally, though not always, become inflected; and the protoplasm
within their cells undergoes aggregation, though the spheres thus
formed are extremely small, with many of the cells partly filled with
brownish muddy matter. In two instances, when leaves were immersed in
water, at a lower temperature than 130 (54 .4 Cent.), which was then
raised to 145 (62 .7 Cent.), they became during the earlier period of
immersion inflected, but on being afterwards left in cold water were
incapable of re-expansion. Exposure for a few minutes to a temperature
of 145o sometimes causes some few of the more sensitive glands to be
speckled with the porcelain-like appearance; and on one occasion this
occurred at a temperature of 140 (60 Cent.). On another occasion,
when a leaf was placed in water at this temperature of only 140o, and
left therein till the water cooled, every gland became like porcelain.
Exposure for a few minutes to a temperature of 150 (65 .5 Cent.)
generally produces this effect, yet many glands retain a
* Traite de Bot. 1874, p. 1034. [page 74]
pinkish colour, and many present a speckled appearance. This high
temperature never causes true inflection; on the contrary, the
tentacles commonly become reflexed, though to a less degree than when
immersed in boiling water; and this apparently is due to their passive
power of elasticity. After exposure to a temperature of 150 Fahr., the
protoplasm, if subsequently subjected to carbonate of ammonia, instead
of undergoing aggregation, is converted into disintegrated or pulpy
discoloured matter. In short, the leaves are generally killed by this
degree of heat; but owing to differences of age or constitution, they
vary somewhat in this respect. In one anomalous case, four out of the
many glands on a leaf, which had been immersed in water raised to 156
(68 .8 Cent.), escaped being rendered porcellanous;* and the protoplasm
in the cells close beneath these glands underwent some slight, though
imperfect, degree of aggregation.
Finally, it is a remarkable fact that the leaves of Drosera
rotundifolia, which flourishes on bleak upland moors throughout Great
Britain, and exists (Hooker) within the Arctic Circle, should be able
to withstand for even a short time immersion in water heated to a
temperature of 145 .**
65