62 DROSERA ROTUNDIFOLIA. Cua. ILL 
effect may be attributed to exosmose; for the leaves in the 
syrup became quite flaccid, and those in the gum and starch 
somewhat flaccid, with their tentacles twisted about in the 
most irregular manner, the longer ones like corkscrews. We 
shall hereafter see that solutions of ‘these substances, when 
placed on the discs of leaves, do not incite inflection. Particles 
of soft sugar were added to the secretion round several glands 
and were soon dissolved, causing a great increase of the secre- 
tion, no doubt by exosmose; and after 24 hrs. the cells showed 
a certain amount of aggregation, though the tentacles wero 
not inflected. Glycerine causes in a few minutes well-pro- 
nounced aggregation, commencing as usual within the glands 
and then travelling down the tentacles; and this I presume 
may be attributed to the strong attraction of this substance 
for water. Immersion for several hours in water causes some 
degree of aggregation. Twenty leaves were first carefully 
examined, and re-examined after having been left immersed 
in distilled water for various periods, with the following results. 
It is rare to find even a trace of aggregation until 4 or 5 
and generally not until several more hours have elapsed. 
When however a leaf becomes quickly inflected in water, as 
sometimes happens, especially during very warm weather, 
aggregation may occur in little over 1 hr. In all cases 
leaves left in water for more than 24 hrs. have their glands 
blackened, which shows that their contents are aggregated; 
and in the specimens which were carefully examined, there 
was fairly well-marked aggregation in the upper cells of the 
pedicels. These trials were made with cut-off leaves, and it 
occurred to me that this circumstance might influence the 
result, as the footstalks would not perhaps absorb water quickly 
enough to supply the glands as they continued to secrete. 
But this view was proved erroneous, for a plant with uninjured 
roots, bearing four leaves, was submerged in distilled water for 
47 hrs., and the glands were blackened, though the tentacles 
were very little inflected. In one of these leaves there was only 
a slight degree of aggregation in the tentacles; in the second 
rather more, the purple contents of the cells being a littlo 
separated from the walls; in the third and fourth, which were 
pale leaves, the aggregation in the upper parts of the pedicels 
was well marked. In these leaves the little masses of proto- 
plasm, many of which were oval, slowly changed their forms 
and ‘positions so that a submergence for 47 hrs. had not killed 
the protoplasm. In a previous trial with a submerged plant 
the tentacles were not in the least indected. 
