440 UTRICULARIA MONTANA. Ghap. XVIII. 



elude that tlie tubers do not serve as reservoirs for 

 food, but for water during the dry season to which the 

 phint 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 4^ by 4^ 

 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 of these shrivelled tubers 



