then placed under a small bell-glass, with a large pinch of the
carbonate. After 10 m. the glands showed a considerable degree of
aggregation, and the protoplasm lining the cells of the pedicels was a
little separated from the walls. Another leaf was left for 50 m. with
the same result, excepting that the hairs became throughout their whole
length of a brownish colour. In a third leaf, which was exposed for 1
hr. 50 m., there was much aggregated matter in the glands; and some of
the masses showed signs of breaking up into brown granular matter. This
leaf was again placed in the vapour, so that it was exposed altogether
for 5 hrs. 30 m.; and now, though I examined a large number of glands,
aggregated masses were found in only two or three; in all the others,
the masses, which before had been globular, were converted into brown,
opaque, granular matter. We thus see that exposure to the vapour for a
considerable time produces the same effects as long immersion in a
strong solution. In both cases there could hardly be a doubt that the
salt had been absorbed chiefly or exclusively by the glands.
On another occasion bits of damp fibrin, drops of a weak infusion of
raw meat and of water, were left for 24 hrs. on some leaves; the hairs
were then examined, but to my surprise differed in no respect from
others which had not been touched by these fluids. Most of the cells,
however, included hyaline, motionless little spheres, which did not
seem to consist of protoplasm, but, I suppose, of some balsam or
essential oil.
Pelargonium zonale (var. edged with white). The leaves [page 351] are
clothed with numerous multicellular hairs; some simply pointed; others
bearing glandular heads, and differing much in length. The glands on a
piece of leaf were examined and found to contain only limpid fluid;
most of the water was removed from beneath the covering glass, and a
minute drop of one part of carbonate of ammonia to 146 of water was
added; so that an extremely small dose was given. After an interval of
only 3 m. there were signs of aggregation within the glands of the
shorter hairs; and after 5 m. many small globules of a pale brown tint
appeared in all of them; similar globules, but larger, being found in
the large glands of the longer hairs. After the specimen had been left
for 1 hr. in the solution, many of the smaller globules had changed
their positions; and two or three vacuoles or small spheres (for I know
not which they were) of a rather darker tint appeared within some of
the larger globules. Little globules could now be seen in some of the
302