122 PLANTS WITH TRAPS AND PITFALLS TO ENSNARE ANIMALS 
common basal cell. The basal cells themselves are intercalated amongst the cells 
lining the bladder. The organic substances from the decaying bodies of captured 
animals are sucked up by these stellate groups of cells, and from them pass into the 
basal cells, and later, into the other adjacent cells of the bladder and those of the 
plant at large. 
The majority of the animals caught by the bladders are crustaceans. It is 
principally larve and adult individuals of small species of Cypris, Daphnia, and 
Cyclops that fall into the trap; but larve of gnats, and various other small 
insects, little worms, and infusoria, are also not infrequently met with imprisoned 
in the bladders. The number of animals captured is comparatively large. In 
single bladders the remnants of no less than twenty-four small crustaceans have 
been observed. The prey secured by Utricularia minor (fig. 17), which lives in 
little pools of still water in peat-bogs, is very abundant. The North American 
Utricularia clandestina seems also to use its capturing apparatus with great 
success. 
What it is that induces the animals to press upon the valves and so fall into the 
trap is not fully explained. We may suppose that they expect to find food in the 
bladder-cavity, or that they hope it will afford a shelter where they can rest for 
a time and be protected from their pursuers. The last suggestion is especially 
supported by the circumstance that the approach to the valve-covered orifice of 
the bladder is guarded against the intrusion of larger animals by stiff sharp bristles 
which stick out from it (fig. 187). Only very small animals, which can easily slip 
in between the relatively large bristles, reach the inside of the bladder, whilst 
larger creatures, which would injure the whole apparatus, are prevented from 
coming near it. Thus; the most probable explanation is that lesser animals pursued 
by greater take refuge in the hiding-places behind the bristles, and so fall into the 
trap. Another very striking fact is that the bladders of Utriculariz, living in still 
water, look delusively like certain Ostracoda, especially species of the genus 
Daphnia. The bladder itself resembles the shell-covered body in size and form, 
and the bristles the antenne and swimmerets of one of these crustaceans. Whether 
there is any significance in this curious similarity of outward appearance must be 
left undecided. 
The majority of Utrieularie live in pools of water beside foot-tracks on moors 
and in the little collections of water between clumps of reeds in peat-bogs; and 
these are precisely the haunts of the little creatures that are to fall into the traps. 
Every handful of water that one scoops up contains hundreds of midge-larve, 
water-fleas, Ostracoda, and one-eyed Cyclops, which rush about promiscuously, 
pursuing and seizing one another. One species of these plants lives in the moun- 
tains of Brazil in the rain-filled receptacles of Tillandsia plants. The Tillandsia 
is allied to the pine-apple, and has rosettes of concave leaves, the latter resting one 
upon the other in such a way as to form a niche or cavity in front of each leaf 
which fills with rain like a cistern. Many different kinds of small animals are 
always swimming about in these little cisterns, and almost every one of the latter 
