temperature kills the leaves and coagulates the albuminous contents of
the glands.
In my observations on Drosera rotundifolia, the leaves seemed to be
more quickly inflected over animal substances, and to remain inflected
for a longer period during very warm than during cold weather. I
wished, therefore, to ascertain whether heat alone would induce
inflection, and what temperature was the most efficient. Another
interesting point presented itself, namely, at what degree life was
extinguished; for Drosera offers unusual facilities in this respect,
not in the loss of the power of inflection, but in that of subsequent
re-expansion, and more especially in the failure of the protoplasm to
become aggregated, when the leaves after being heated are immersed in a
solution of carbonate of ammonia.*
* When my experiments on the effects of heat were made, I was not aware
that the subject had been carefully investigated by several observers.
For instance, Sachs is convinced ( Traite de Botanique, 1874, pp. 772,
854) that the most different kinds of plants all perish if kept for 10
m. in water at 45 to 46 Cent., or 113 to 115 Fahr.; and he
concludes that the protoplasm within their cells always coagulates, if
in a damp condition, at a temperature of between 50 and 60 Cent., or
122 to 140 Fahr. Max Schultze and Kuhne (as quoted by Dr. Bastian in
Contemp. Review, 1874, p. 528) found that the protoplasm of
plant-cells, with which they experimented, was always killed and [[page
67]] altered by a very brief exposure to a temperature of 118 1/2
Fahr. as a maximum. As my results are deduced from special phenomena,
namely, the subsequent aggregation of the protoplasm and the
re-expansion of the tentacles, they seem to me worth giving. We shall
find that Drosera resists heat somewhat better than most other plants.
That there should be considerable differences in this respect is not
surprising, considering that some low vegetable organisms grow in hot
springs cases of which have been collected by Prof. Wyman ( American
Journal of Science, vol. xliv. 1867). Thus, Dr. Hooker found Confervae
in water at 168 Fahr.; Humboldt, at 185 Fahr.; and Descloizeaux, at
208 Fahr.) [page 67]
[My experiments were tried in the following manner. Leaves were cut
58