THE COMMON TEASEL AS A CARNIVOROUS PLANT 
45 
containing a liquor, secreted b}' - the plant itself, which attracts 
insects, whose escape is prevented by retaining-hairs at the entrance 
and by a more-or-less complete lid. The insects are then drowned 
and become putrid, after which their products are absorbed by the 
plant. 
(8)—In ZJtricularia, a genus of small floating (rootless) aquatic 
plants of which two species are fairly common in Britain, the method 
employed is surprisingly ingenious. The plant has on its leaves 
many small bladders, each of which is provided at the entrance with 
a trap-door surrounded by hairs. When any wandering creature, 
however small, approaches the entrance, guided by the surrounding 
hairs, it touches one special hair which is sensitive. This, acting 
like a trigger, causes the trap-door to open suddenly inwards, thus 
causing a sharp current of water to enter the bladder, carrying with 
it the tiny creature in question. This is at once imprisoned and 
retained by the re-closing of the trap-door, and is then digested at 
leisure. Attention has been called only recently to the working of 
this highly-ingenious piece of mechanism by Mr. C. L. Withycombe 
(Knowledge , xxxix. 1916, pp. 238-241). Earlier observers, includ¬ 
ing Darwin, had supposed that the prey forced its way into the 
bladders, attracted by some sweet substance secreted inside. 
(4)—In Dipscicus a totally-different and simpler method is 
employed. The plant has neither pitchers, nor bladders, nor any 
partially-closed receptacles provided with lids, trap-doors, or retaining- 
hairs at their entrances. On the contrary, its cups in which insects 
are captured are widely open at the top and the liquor contained in 
them is certainly derived—in the main, at any rate—from falling- 
rain and dew. Yet it seems to contain some sweet toxic substance 
(excreted, apparently, by the plant itself) which attracts and stupefies 
many small creatures; while the structure of the cups is such as to 
facilitate their capture, drowning, and putrefaction, leading, ultimately, 
to the absorption b}^ the plant of the resulting highly-nitrogenous 
product. A somewhat similar method is employed in Billbergia 
(Order J3romeJiacece ), of which there are many species, all epiphytic 
on trees, in the West Indies and northern South America. Water is 
caught and retained by the bases of the leaves, though these do not 
form true cups. In this, many insects and other creatures become 
drowned, and these putrefying, soon render it highly offensive. 
The extraordinary variety of creatures thus caught has been investi¬ 
gated by C. Picardo (Bull. Scient. France et Belg. xlvii. 1913, 
pp. 215-360), H. Scott ( Zoologist , 1914, pp. 183-195), and D. J. 
Scourlield (Journ. Queckett Microscop. Club, ser. 2, viii. 1903, 
p. 539). Mr. J. L. North, Curator of the Boyal Botanic Society, 
informs me he has heard a man relate how once, travelling in Brazil, 
he had passed beneath a tree the branches of which were covered with 
plants of Billbergia in full flower, and, reaching up with his riding- 
crop to pull down some blossoms, had been at once drenched with 
putrid evil-smelling liquor ! 
