362 
POPULAR SCIENCE REVIEW. 
Besides Drosera and Dioncea , there are four other genera in- 
cluded in the order Droseraceae, viz., Aldrovanda , Droso- 
phyllum , Byblis , and Roridula , all of which capture insects ; 
and in all of them the phenomena of absorption and digestion 
have either been observed or may be fairly inferred. The first of 
these genera includes only a single species, A. vesiculosa , oc- 
curring in three somewhat distinct forms in Europe, India, and 
Australia. It is a small water-plant, with two-lobed leaves, 
having the peculiarity of suddenly closing on irritation similar 
to that of Dioncea , and furnished with long jointed hairs, 
which are apparently sensitive. Of the remaining three genera, 
one is European, another South African, and the third Aus- 
tralian. The first only has yet been examined in the growing 
state, and bears a strong resemblance to Drosera , except that 
the tentacles have no power of movement. 
To the order Lentibulariacese belong the four genera, 
Pinguicula , TJtricularia , Polypompholyx, and Genlisea , all car- 
nivorous. The genus TJtricularia , or Bladder wort, is a very 
interesting one, and includes three or four British species, plants 
found in ditches, often of fetid water, with elegant yellow flowers 
on slender stalks, and floating deeply-divided leaves furnished 
with little bladders, from whence the plant derives its name. 
These bladders have been recognised by several observers, Mr. 
R. Holland in this country and Mrs. Treat in the United States, 
as fly-traps, and their structure has been closely investigated 
by Mr. Darwin in the case of the commonest British species, 
U. vulgaris , and its variety or sub-species U. neglecta. The 
bladders are about one-tenth of an inch in diameter, are pro- 
vided with a number of long bristles or 44 antennae,” and are 
closed by a valve which is attached on all sides to the bladder, 
except by its posterior margin, which is free, and forms one side 
of the slit-like orifice which leads into the bladder. The valve 
is covered on the inner surface with a number of glands which 
secrete, but apparently have no power of absorption. The mar- 
gin of the valve rests on the edge of a rim or collar, which 
allows the valve to open inwards only. By this contrivance a 
large number of aquatic animals are entrapped — insects, En- 
tomostraca, and even worms, as well as innumerable Algae and 
Infusoria; and obviously, when once captured, cannot again 
escape. Mr. Darwin’s observations serve to show beyond doubt 
that the bladders have the power of absorbing nitrogenous sub- 
stances, which they doubtless derive from the decay of the im- 
prisoned animalcules ; but he does not consider that they have 
any power of digesting animal matter analogous to that pos- 
sessed by the plants already described. This absorption he 
believes to be effected by certain peculiar bodies described by 
him as 64 bifids ” and 44 quadrifids.” These bodies line the whole 
