secretion its power of dissolving albuminous compounds.
Splinters of clean glass were scattered on a large number of leaves,
and these became moderately inflected. They were cut off and divided
into three lots; two of them, after being left for some time in a
little distilled water, were strained, and some dis-
* Sachs remarks ( Traite de Bot. 1874, p. 774), that cells which are
killed by freezing, by too great heat, or by chemical agents, allow all
their colouring matter to escape into the surrounding water. [page 97]
coloured, viscid, slightly acid fluid was thus obtained. The third lot
was well soaked in a few drops of glycerine, which is well known to
dissolve pepsin. Cubes of albumen (1/20 of an inch) were now placed in
the three fluids in watch-glasses, some of which were kept for several
days at about 90 Fahr. (32 .2 Cent.), and others at the temperature of
my room; but none of the cubes were dissolved, the angles remaining as
sharp as ever. This fact probably indicates that the ferment is not
secreted until the glands are excited by the absorption of a minute
quantity of already soluble animal matter, a conclusion which is
supported by what we shall hereafter see with respect to Dionaea. Dr.
Hooker likewise found that, although the fluid within the pitchers of
Nepenthes possesses extraordinary power of digestion, yet when removed
from the pitchers before they have been excited and placed in a vessel,
it has no such power, although it is already acid; and we can account
for this fact only on the supposition that the proper ferment is not
secreted until some exciting matter is absorbed.
On three other occasions eight leaves were strongly excited with
albumen moistened with saliva; they were then cut off, and allowed to
soak for several hours or for a whole day in a few drops of glycerine.
Some of this extract was added to a little hydrochloric acid of various
strengths (generally one to 400 of water), and minute cubes of albumen
were placed in the mixture.* In two of these trials the cubes were not
in the least acted on; but in the third
* As a control experiment bits of albumen were placed in the same
glycerine with hydrochloric acid of the same strength; and the albumen,
as might have been expected, was not in the least affected after two
86