PLANTS WITH TRAPS AND PITFALLS TO ENSNARE ANIMALS. 135 



natives of Borneo) this fringe of sharp teeth looks like the set of teeth of a beast 

 of prey; and in Nepenthes villosa, of which a pitcher is represented in fig. 21 *, a 

 double row of bigger and smaller teeth directed towards the bottom of the pitcher 

 is developed, and renders the escape of prey, once caught in the trap, impossible. 



Most of the creatures that fall into the pitchers are, however, speedily drowned 

 in the large quantity of liquid at the bottom. For a third part or even a half of 

 the cavity is filled with liquid. This liquid originates from special gland-cells on 

 the inner surface of the pitcher, consists mainly of water, and so long as there are 

 no animals in the pitfall, gives only a very weak acid reaction. But as soon 

 as the body of an animal reaches the bottom, more fluid is secreted. This has 

 a distinctly acid taste, possesses the power of dissolving albuminous substances, 

 such as flesh and coagulated blood, and corresponds, not only in respect of this 

 action but also in chemical composition, to the gastric juice. For, in addition to 

 organic acids (malic, citric, and formic acids), an organic body like pepsin has 

 been detected in it, and nitrogenous organic compounds have been brought into 

 solution in it artificially as well. If the liquid from a Nepenthes pitcher, which has 

 not yet captured any animal, is poured into a glass vessel containing a small piece 

 of meat, the flesh is at first but little afifected ; but, if a few drops of formic acid are 

 added, the flesh is dissolved and undergoes the very same changes as it does in the 

 stomach of a mammal. The process going on in the pitchers of Nepenthes when 

 animals fall into them is therefore not only analogous to digestion, but may be 

 properly designated digestion. 



The digested portions of the bodies are afterwards absorbed by special cells at 

 the bottom, and on the lower parts of the lining wall of the Nepenthes pitchers. 



Another series of plants was at one time regarded as belonging to our present 

 section of carnivorous plants. These include forms possessing subterranean stem 

 structures, bearing hollow, scale-like leaves, or leaves so arranged that chink-like 

 spaces exist between them. Into these chambers or spaces it was supposed that 

 minute animals, Infusoria, Rhizopods, Aphides, and the like found their way, and 

 that here they met their death, their bodies being digested through the agency 

 of peculiar glands which line the walls of these chinks and spaces. Though this 

 view of the carnivorous function of these subterranean organs has failed to become 

 established on a solid basis of fact, the plants in question are of considerable 

 interest and may be conveniently treated here. 



One of the most remarkable of the plants belonging to this group is the Tooth- 

 wort {Lathrcea Squamaria), of which we shall repeatedly have occasion to speak. 

 It is nearly allied to the Yellow-Rattle and Cow-wheat, but it is destitute of 

 chlorophyll, and lives underground, parasitic on the roots of arborescent Angio- 

 sperms, except during a brief period annually when it sends up above-ground a few 

 short shoots covered with flowers. The subterranean stems are white, have a 

 fleshy, solid, and elastic appearance, and are covered throughout their entire length 

 with thick squamous leaves placed closely one above the other (see fig. 25 ^ and 

 fig. 37). In colour and consistence these leaves are like the stem; in outline they 



