the protoplasm in solution. There is still stronger evidence that
aggregation is independent of secretion; for the papillae, described in
the first chapter, with which the [page 57] leaves are studded are not
glandular, and do not secrete, yet they rapidly absorb carbonate of
ammonia or an infusion of raw meat, and their contents then quickly
undergo aggregation, which afterwards spreads into the cells of the
surrounding tissues. We shall hereafter see that the purple fluid
within the sensitive filaments of Dionaea, which do not secrete,
likewise undergoes aggregation from the action of a weak solution of
carbonate of ammonia.
The process of aggregation is a vital one; by which I mean that the
contents of the cells must be alive and uninjured to be thus affected,
and they must be in an oxygenated condition for the transmission of the
process at the proper rate. Some tentacles in a drop of water were
strongly pressed beneath a slip of glass; many of the cells were
ruptured, and pulpy matter of a purple colour, with granules of all
sizes and shapes, exuded, but hardly any of the cells were completely
emptied. I then added a minute drop of a solution of one part of
carbonate of ammonia to 109 of water, and after 1 hr. examined the
specimens. Here and there a few cells, both in the glands and in the
pedicels, had escaped being ruptured, and their contents were well
aggregated into spheres which were constantly changing their forms and
positions, and a current could still be seen flowing along the walls;
so that the protoplasm was alive. On the other hand, the exuded matter,
which was now almost colourless instead of being purple, did not
exhibit a trace of aggregation. Nor was there a trace in the many cells
which were ruptured, but which had not been completely emptied of their
contents. Though I looked carefully, no signs of a current could be
seen within these ruptured cells. They had evidently been killed by the
pressure; and the matter which they [page 58] still contained did not
undergo aggregation any more than that which had exuded. In these
specimens, as I may add, the individuality of the life of each cell was
well illustrated.
A full account will be given in the next chapter of the effects of heat
on the leaves, and I need here only state that leaves immersed for a
short time in water at a temperature of 120 Fahr. (48 .8 Cent.),
which, as we have seen, does not immediately induce aggregation, were
then placed in a few drops of a strong solution of one part of
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