4140 UTRICULARIA MONTANA. Cuap. XVIIL 
elude that the tubers do not serve as reservoirs for 
food, but for water during the dry season to which the 
plant is probably exposed. The many little bladders 
filled with water would aid towards the same end. 
To test the correctness of this view, a small plant, 
growing in light peaty earth in a pot (only 44 by 44 
inches outside measure) was copiously watered, and 
then kept without a drop of water in the hothouse. 
Two of the upper tubers were beforehand uncovered 
and measured, and then loosely covered up again. In 
a fortnight’s time the earth in the pot appeared ex- 
tremely dry ; but not until the thirty-fifth day were 
the leaves in the least affected; they then became 
slightly reflexed, though still soft and green. This 
plant, which bore only ten tubers, would no doubt 
have resisted the drought for even a longer time, 
had I not previously removed three of the tubers 
and cut off several long rhizomes. When, on the 
thirty-fifth day, the earth in the pot was turned out, 
it appeared as dry as the dust on a road. All the 
tubers had their surfaces much wrinkled, instead of 
being smooth and tense. They had all shrunk, but I 
cannot say accurately how much; for as they were at 
first symmetrically oval, I measured only their length 
and thickness; but they contracted in a transverse 
line much more in one direction than in another, so as 
to become greatly flattened. One of the two tubers 
which had been measured was now three-fourths of 
its original length, and two-thirds of its original thick- 
ness in the direction in which it had been measured, 
but in another direction only one-third of its former 
thickness. The other tuber was one-fourth shorter, one- 
eighth less thick in the direction in which it had been 
measured, and only half as thick in another direction. 
A slice was cut from one cf these shrivelled tubers 
