356 UTRICULARIA MONTANA. (Cuap, XVIII. 
measured only their length and thickness; but they con- 
tracted 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 thickness 
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 and 
examined. The cells still contained much water and no air, 
but they were more rounded or less angular than before, and 
their walls not nearly so straight; it was therefore clear 
that the cells had contracted. The tubers, as long as 
they remain alive, have a strong attraction for water; 
the shrivelled one, from which a slice had been cut, was 
left in water for 22 hrs. 30 m., and its surface became as 
smooth and tense as it originally was. On the other hand, 
a shrivelled tuber, which by some accident had been separated 
from its rhizome, and which appeared dead, did not swell in 
the least, though left for several days in water. 
With many kinds of plants, tubers, bulbs, &., no doubt 
serve in part as reservoirs for water, but I know of no case, 
besides the present one, of such organs having been developed 
solely for this purpose. Prof. Oliver informs me that two or 
three other species of Utricularia are provided with these 
appendages; and the group containing them has in conse- 
quence received the name of orchidioides. All the other 
species of Utricularia, as well as of certain closely related 
genera, are either aquatic or marsh plants; therefore, on the 
principle of nearly allied plants generally having a similar 
constitution, a never-failing supply of water would probably 
be of great importance to our present species. We can thus 
understand the meaning of the development of its tubers, 
and of their number on the same plant, amounting in one 
instance to at least twenty. 
UTRICULARIA NELUMBIFOLIA, AMETHYSTINA, GRIFFITHII, 
CHRULEA, ORBICULATA, MULTICAULIS [cornura ]. 
As I wished to ascertain whether the bladders on the 
rhizomes of other species of Utricularia, and of the species 
