PLANTS WITH TRAPS AND PITFALLS TO ENSNARE ANIMALS. 123 



is the sphere of activity of an individual Utricularia nelumbifolia. This plant 

 is remarkable also from the fact that long runners are thrown out from its stems, 

 which grow across, in wide arches, from its cistern to a neighbouring Tillandsia, 

 where it selects one of the reservoirs in the rosettes as a new site and dips down 

 into the water a fantastic method of propagation of which we shall speak again 

 on another occasion. 



A few Utricularise do not live in water at all, but grow amongst mosses, liver- 

 worts, and lycopods, in the vegetable mould filling the clefts and crevices of rocks, 

 and the bark-fissures of old trees. Of this habit, for example, is the pretty 

 Brazilian Utricularia montana, which, in spite of the difference of its habitat, is 

 provided with an apparatus for capturing animals agreeing in all essential respects 

 with the description already given. The bladders used by these plants for pur- 

 poses of prey are produced on subterranean filiform stems which thread their way 

 in the vegetable mould and wefts of decaying moss-stems, and here and there swell 

 into tubers. The bladders are hyaline and transparent, and are filled with watery 

 liquid, sometimes also with air. They are only 1 millimeter in diameter, but are 

 present in large numbers. The entrance into these bladders is much more con- 

 cealed than in the species that live in water. The dorsal surface of the bladder 

 being still more strongly curved, the position of the orifice is altered so as to be 

 quite close to the little stalk of the bladder. In addition, the orifice is, as it were, 

 roofed over, and thereby protected against the possibility of being stopped up by 

 particles of earth, and the passage leading to it is very narrow. That, in spite of 

 the difficulty of entrance, a number of minute animals do seek a hiding-place here 

 is proved by the circumstance that, besides various infusoria, rhizopoda, and 

 creatures of that kind inhabiting damp earth, species of Acarus and larvae of 

 other animals have been found, both dead and alive, in the bladders. 



With this first group of insectivorous plants, wherein the capturing apparatus 

 includes a valve to prevent the egress of such animals as fall into the trap, is 

 associated in the first section a second group, viz. that of the ascidia-bearing or 

 pitcher-plants, in which the foliage -leaves are converted into pitfalls, and the 

 escape of the captured prey prevented by a number of points lining the inner 

 wall of the cavity, and directed from the aperture towards the closed bottom. 

 There is an extraordinary variety in the form of the pitfalls. Sometimes they 

 are tubular, utricular, or funnel-shaped cavities, sometimes mug or pitcher-shaped, 

 or urceolate; in some cases these are straight, in others bowed like sickles, or 

 spirally twisted. They always arise from the part of the petiole upon which the 

 lamina immediately rests. The lamina is always relatively small, being represented 

 in the majority of the traps by a scale or lobe, and it only appears to be an 

 appendage of the large expanded and hollowed -out petiole. In many pitcher- 

 plants the little lamina looks like a lid placed over the orifice to the pitfall, as, 

 for instance, is shown in the illustration (fig. 21 4 ), whilst in others (Nepenthes 

 ampullaria and N. vittata) it has the form of a handle or stalk, and serves as a 

 place for animals visiting the pitchers to alight upon. 



