Car. 1V. THE EFFECTS OF HEAT. 67 
My experiments were tried in the following manner. Leaves 
were cut off, and this does not in the least interfere with their 
powers; for instance, three cut-off leaves, with bits of meat 
placed on them, were kept in a damp atmosphere, and after 
23 hrs. closely embraced the meat both with their ten- 
tacles and blades; and the protoplasm within their cells was 
well aggregated. Three ounces of doubly distilled water was 
heated in a porcelain vessel, with a delicate thermometer 
having a long bulb obliquely suspended in it. The water was 
gradually raised to the required temperature by a spirit-lamp 
moved about under the vessel; and in all cases the leaves 
were continuaily waved for some minutes close to the bulb. 
They were then placed in cold water, or in a solution of car- 
bonate of ammonia. In other cases they were left in the water, 
which had been raised to a certain temperature, until it cooled. 
Again in other cases the leaves were suddenly plunged into 
water of a certain temperature, and kept there for a specified 
time. Considering that the tentacles are extremely delicate, 
and that their coats are very thin, it seems scarcely possible 
that the fluid contents of their cells should not have been 
heated to within a degree or two of the temperature of the 
surrounding water. Any further precautions would, I think, 
have been superfluous, as the leaves from age or constitutional 
causes differ slightly in their sensitiveness to heat. 
It will be convenient first briefly to describe the effects of 
immersion for thirty seconds in boiling water. The leaves are 
rendered flaccid, with their tentacles bowed backwards, which, 
as we shall see in a future chapter, is probably due to their 
outer surfaces retaining their elasticity for a longer period than 
their inner surfaces retain the power of contraction. The 
purple fluid within the cells of the pedicels is rendered finely 
granular, but there is no true aggregation; nor does this follow 
altered by a very! brief expo- 
sure to a temperature of 1183° 
Fahy. as a maximum.” As my 
results are deduced from special 
phenomena, namely, the subse- 
quent aggregation of the proto- 
plasm 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 consider- 
able 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 Conferve in 
water at 168° Fahr.; Humboldt, 
at 185° Fahr.; and Descloizeaux, 
at 208° Fahr. 
