Guar. IV.] THE EFFECTS OF HEAT. 57 
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 tentacles 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 along 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 continually waved for 
some minutes close to the bulb. They were then placed in cold water, 
or in a solution of carbonate 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 con- 
stitutional causes differ slightly in their sensitiveness to heat. 
It will be convenient first briefly to describe the eflects of immersion 
for thirty seconds in boiling water. ‘lhe 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 docs 
this follow when the leaves are subsequently placed in a solution of 
carbonate of ammonia. But the most remarkable change is that the 
glands become opaque and uniformly white; and this may be attri- 
buted to the coagulation of their albuminous contents. 
My first and preliminary experiment consisted in putting seven 
leaves in the same vessel of water, and warming it slowly up to the 
temperature of 110° Fahr. (48°°3 Cent.); a leaf heing taken out as 
soon as the temperature rose to 80° (26°°6 Cent.), another at 85°, 
another at 90°, and soon. Lach leaf when taken out, was placed in 
water at the temperature of my room, and the tentacles of all soon 
became slightly, though irregularly, inflected. They were now re- 
moved from the cold water and kept in damp air, with bits of meat 
placed on their discs, The leaf which had been exposed to the tem- 
perature of 110° became in 15 m. greatly inflected ; and in 2 hrs. every 
single tentacle closely embraced the meat. So it was, but after rather 
longer intervals, with the six other leaves. It appears, therefore, 
that the warm bath had increased their sensitiveness when excited by 
meat. 
I next observed the degree of inflection which leaves underwent 
within stated periods, whilst still immersed in warm water, kept as 
