. Cnar. IV, THE EFFECTS OF HEAT. 69 
ammonia, and the glands quickly became black, with strongly 
marked aggregation in the tentacles, showing that the proto- 
plasm was alive, and that the glands had not lost their power of 
absorption. Another leaf was placed in water at 110° (48°3 
Cent.) which was raised to 120° (48°'8 Cent.); and every ten- 
tacle, excepting one, was quickly and closely inflected. This leaf 
was now immersed in a few drops of a strong solution of car- 
bonate of ammonia (one part to 109 of water); in 10 m. all the 
glands became intensely black, and in 2 hrs. the protoplasm in 
the cells of the pedicels was well aggregated. Another leaf was 
suddenly plunged, and as usual waved about, in water at 120°, 
and the tentacles became inflected in from 2m. to 3m., but 
only so as to stand at right angles to the disc. The leaf was 
now placed in the same solution (viz. one part of carbonate of 
ammonia to 109 of water, or 4 grs. to 1 oz., which I will for 
the future designate as the strong solution), and when I looked 
at it again after the interval of an hour, the glands were 
blackened, and there was well-marked aggregation. After an 
additional interval of 4 hrs. the tentacles had become much 
more inflected. It deserves notice that a solution as strong as 
this never causes inflection in ordinary cases. Lastly a leaf 
was suddenly placed in water at 125° (51°6 Cent.), and was 
left in it until the water cooled; the tentacles were rendered 
of a bright red and soon became inflected. The contents of 
the cells underwent some degree of aggregation, which in 
the course of three hours increased; but the masses of proto- 
plasm did not become spherical, as almost always occurs with 
leaves immersed in a solution of carbonate of ammonia. 
We learn from these cases that a temperature of 
from 120° to 125° (48°8 to 51°6 Cent.) excites the 
tentacles into quick movement, but does not kill the 
leaves, as shown either by their subsequent re-expansion 
or by the aggregation of the protoplasm. We shall 
now see that a temperature of 130° (54°-4 Cent.) is too 
high to cause immediate inflection, yet does not kill 
the leaves. 
Experiment 1—A leaf was plunged, and as in all cases 
waved about for a few minutes, in water at 180° (54°°4 Cent.), 
but there was no trace of inflection; it was then placed in cold 
water, and after an interval of 15 m. very slow movement wat 
