56 DROSERA ROTUNDIFOLIA. (Cuap. IV. 
CHAPTER IV. 
THE EFFECTS OF HEAT ON THE LEAVES. 
Nature of the experiments—Etfects of boiling water—Warm water causes 
rapid inflection—Water at a higher temperature does not cause immediate 
inflection, but does not kill the leaves, as shown by their subsequent 
re-expansion and by the aggregation of the protoplasm—A still higher 
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 proto- 
plasm 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 ob- 
servers. For instance, Sachs is con- 
vinced (‘Traité 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 condi- 
tion,at a temperature of between 50° 
and 60° Cent., or 122° to 140° Fahr. 
Max Schultze and Kühne (as quoted 
by Dr. Bastian in ‘ Contemp. Review,’ 
1874, p. 528) “found that the pro- 
toplasm of plant-cells, with which 
they experimented, was always killed 
and altered by a very brief exposure 
to a temperature of 1184° 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 re- 
spect 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 
Conferve in water at 168° Fahr. ; 
Humboldt, at 185° Fahr.; and Des- 
cloizeaux, at 208° Fahr. 
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