126 PLANTS WITH TRAPS AND PITFALLS TO ENSNARE ANIMALS. 



and turn their concave surfaces towards falling rain. They serve, moreover, at 

 least in Sarracenia purpurea, to catch the drops of rain, which then flow down 

 into the bottom of the ascidia and fill them more or less with water. There is 

 very little evaporation from the hollow pitchers; and even when there has been no 

 rain for a week, one always finds some of the previously-collected water at the 

 bottom. The inner surface of a pitcher is lined by cells arranged like the scales 

 of enamel on a pike's back (see fig. 19 2 ). The internally-projecting wall of each 

 of these scales is transformed into a stiff decurved point, and the lower the position 

 of the cells the longer do the points become. The shell-like lamina again, above 

 the contracted orifice, bears glandular hairs which exude honey, so that the parts 

 surrounding the aperture are covered by a thin film of sweet juice. 



Many animals are attracted by this honey. Some are winged and alight from 

 flying; others, being wingless, make use of a peculiar ridge, which projects on the 

 concave side of the utricle, to help them to creep up the latter. If these honey- 

 eaters happen to travel away from the lamina to that part of the pitcher which 

 is lined with the smooth and slippery decurved cells, they are as good as lost. 

 They slip down over the brink, every attempt to climb up again being rendered 

 futile by the downwardly-pointing needles which clothe the lower part of the wall; 

 and ultimately they fall into the water collected at the bottom, where they are 

 drowned and their bodies putrefy. The products of decay are absorbed as 

 nutriment by the epidermal cells in this region. The number of animals meeting 

 with this fate is often so great that an offensive odour, arising from the decaying 

 bodies, is emitted by the utricles and is noticeable at a considerable distance. In 

 the wild state, the ascidiform utricles are often half-full of drowned animals and 

 it is stated that in these circumstances bird§_also put in an appearance and pick 

 some of the dead remains Mt^oTtheutricles. 



Whether the liquid filling the bottom of the pitchers consists simply of rain- 

 water, or whether the latter is modified by a secretion originating in the gland- 

 like groups of cells there (see fig. 28 7 ), is still uncertain. A centipede over 

 4 centimeters long having fallen into a utricle of Sarracenia purpurea in the 

 night was found only half immersed in the water. The upper half of the creature 

 projected above the liquid, and made violent efforts to escape; but the lower part 

 had, after a few hours, not only become motionless but had turned white from the 

 effect of the surrounding liquid; it appeared to be macerated, and exhibited 

 alterations which are not produced in so short a time in centipedes immersed in 

 ordinary rain-water. When a number of captured animals are undergoing putre- 

 faction at the same time in a pitfall, the liquid turns brown and has the appearance 

 of manure-liquor. 



There is a great difference between the utricles of Sarracenia purpurea and the 

 apparatus adapted to the capture of prey in the plants of which we have chosen as 

 examples, Sarracenia variolaris, a native of the marshes of Alabama, Florida, and 

 Carolina, and the Barlingtonia Calif ornica, found growing at a height of from 300 

 to 1000 meters above the sea on moorlands in California from the borders of 



