Onur. L SYRUCTURE OF THE LEAVES. 7 
Within this layer of cells there is an inner one of differently 
shaped ones, likewise filled with purple fluid, but of a slightly 
different tint, and differently affected by chloride of gold. These 
two layers are sometimes well seen when a gland has been 
crushed or boiled in caustic potash. According to Dr. Warming, 
there is still another layer of much more elongated cells, as 
shown in the accompanying section (fig. 3) copied from his 
work; but these cells were not seen by Nitschke, nor by me. 
In the centre there is a group of elongated, cylindrical cells of 
unequal lengths, bluntly pointed at their upper ends, truncated 
or rounded at their lower ends, closely pressed together, and 
remarkable from being surrounded by a spiral line, which can be 
separated as a distinct fibre. 
These latter cells are filled with limpid fluid, which after long 
immersion in alcohol deposits much brown matter. I presume 
that they are actually connected with the spiral vessels which run 
up the tentacles, for on several occasions the latter were seen to 
divide into two or three excessively thin branches, which could 
be traced close up to the spiriferous cells. ‘Their development 
has been described by Dr. Warming. Cells of the same kind 
have been observed in other plants, as I hear from Dr. Hooker, 
and were seen by me in the margins of the leaves of Pinguicula. 
Whatever their function may be, they are not necessary for the 
secretion of the digestive fluid, or for absorption, or for the 
communication of a motor impulse to other parts of the leaf, 
as we may infer from the structure of the glands in some other 
genera of the Droseracez. 
The extreme marginal tentacles differ slightly from the others. 
Their bases aro broader, and besides their own vessels, they 
receive a fine branch from those which enter the tentacles 
on each side. Their glands are much elongated, and lie em- 
bedded on the upper surface of the pedicel, instead of standing 
at the apex. In other respects they do not differ essentially 
from the oval ones, and in one specimen I found every possible 
transition between the two states. In another specimen there 
were no long-headed glands. These marginal tentacles lose 
their irritability earlier than the others; and when a stimulus 
is applied to the centre of the leaf, they are excited into action 
after the others. When cut-off leaves are immersed in water, 
they alone often become inflected. 
The purple fluid or granular matter which fills the cells ot 
the glands differs to a certain extent from that within the 
cells of the pedicels. For when a leaf is placed in hot water or in 
certain acids, the glands become quite white and opaque, whereaa 
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