48 DROSERA ROTUNDIFOLIA. (Cuap. III. 
secrete, and the aggregated masses of protoplasm are then 
redissolved. Moreover, when leaves are immersed in dense 
vegetable solutions, or in glycerine, the fluid within the 
gland-cells passes outwards, and there is aggregation; and 
when the leaves are afterwards immersed in water, or in an 
innocuous fluid of less specific gravity than water, the 
protoplasm is redissolved, and this, no doubt, is due to 
endosmose. 
Opposed to this view, that aggregation is caused by the 
outward passage of fluid from the cells, are the following 
facts. There seems no close relation between the degree of 
increased secretion and that of aggregation. Thus a particle 
of sugar added to the secretion round a gland causes a much 
greater increase of secretion, and much less aggregation, than 
does a particle of carbonate of ammonia given in the same 
manner. It does not appear probable that pure water would 
cause much exosmose, and yet aggregation often follows from 
an immersion in water of between 16 hrs. and 24 hrs., and 
always after from 24 hrs. to 48 hrs. Still less probable is it 
that water at a temperature of from 125° to 130° Fahr. 
(51°°6 to 54°:4 Cent.) should cause fluid to pass, not only 
from the glands, but from all the cells of the tentacles down 
to their bases, so quickly that aggregation is induced within 
2m.or3m. Another strong argument against this view is, 
that, after complete aggregation, the spheres and oval masses 
of protoplasm float about in an abundant supply of thin, 
colourless fluid; so that at least the latter stages of the 
process cannot be due to the want of fluid to hold the proto- 
plasm in solution. There is still stronger evidence that 
aggregation is independent of secretion; for the papille, 
described in the first chapter, with which the 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 Dionza, which do not secrete, like- 
wise 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 
