were next used, viz. one part to 109 of water; and as the same-sized
drops were given as before, each drop contained 1/1200 of a grain
(.0539 mg.) of either salt. Two cubes of albumen (each about 1/40 of an
inch, or .635 mm.) were placed on the same leaf, and two on another.
Each leaf received, as soon as the secretion became slightly acid (and
this occurred four times within 24 hrs.), drops either of the soda or
potash, and the acid was thus effectually neutralised. The experiment
now succeeded perfectly, for after 22 hrs. the angles of the cubes were
as sharp as they were at first, and we know from experiment 5 that such
small cubes would have been completely rounded within this time by the
secretion in its natural state. Some of the fluid was now removed with
blotting-paper from the discs of the leaves, and minute drops of
hydrochloric acid of the strength of the one part to 200 of water was
added. Acid of this greater strength was used as the solutions of the
alkalies were stronger. The [page 96] process of digestion now
commenced, so that within 48 hrs. from the time when the acid was given
the four cubes were not only completely dissolved, but much of the
liquefied albumen was absorbed.
Experiment 11. Two cubes of albumen (1/40 of an inch, or .635 mm.) were
placed on two leaves, and were treated with alkalies as in the last
experiment, and with the same result; for after 22 hrs. they had their
angles perfectly sharp, showing that the digestive process had been
completely arrested. I then wished to ascertain what would be the
effect of using stronger hydrochloric acid; so I added minute drops of
the strength of 1 per cent. This proved rather too strong, for after 48
hrs. from the time when the acid was added one cube was still almost
perfect, and the other only very slightly rounded, and both were
stained slightly pink. This latter fact shows that the leaves were
injured,* for during the normal process of digestion the albumen is not
thus coloured, and we can thus understand why the cubes were not
dissolved.]
From these experiments we clearly see that the secretion has the power
of dissolving albumen, and we further see that if an alkali is added,
the process of digestion is stopped, but immediately recommences as
soon as the alkali is neutralised by weak hydrochloric acid. Even if I
had tried no other experiments than these, they would have almost
sufficed to prove that the glands of Drosera secrete some ferment
analogous to pepsin, which in presence of an acid gives to the
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