Cair. XVII.] STRUCTURE OF THE BLADDER. 821 
inhabit, as more than one observer has remarked to me, 
remarkably foul ditches. 
The bladders offer the chief point of interest. There are 
often two or three on the same divided leaf, generally near 
the base ; though I have seen a single one growing from the 
stem. ‘They are supported on short footstalks. When fully 
grown, they are nearly 75 of an inch (2°54 mm.) in length. 
They are translucent, of a green colour, and the walls are 
formed of two layers of cells. The exterior cells are poly- 
gonal and rather large; but at many of the points where the 
angles meet, there are smaller rounded cells. These latter 
support short conical projections, surmounted by two hemi- 
spherical cells in such close apposition that they appear 
Fig. 18. 
(Utricularia neglecta.) 
Bladder; much enlarged. c, collar indistinctly seen through the walls. 
united ; but they often separate a little when immersed in 
certain fluids. The papille thus formed are exactly like 
those on the surfaces of the leaves. Those on the same 
bladder vary much in size; and there are a few, especially 
on very young bladders, which have an elliptical instead of 
a circular outline. The two terminal cells are transparent, 
but must hold much matter in solution, judging from the 
area coagulated by prolonged immersion in alcohol or 
ether. 
The bladders are filled with water. They generally, but 
by no means always, contain bubbles of air. According to 
the quantity of the contained water and air, they vary much 
f è 
