PLANTS WITH TRAPS AND PITFALLS TO ENSNARE ANIMALS. 135 



natives of Borneo) this fringe of sharp teeth looks Hke 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 quantit}?^ 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 aflected ; 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 Ijy special cells at 

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



The third group included in the first section of carnivorous plants comprises 

 forms with scale-like leaves, within which are peculiar cavities penetrable by 

 minute animals only, on account of the narrowness of the entry. Special con- 

 trivances to prevent the escape of the prey are absent. The animals are retained 

 and drained of their juices in the cavities by means of protoplasmic filaments 

 radiating from special cells. 



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 entii-e 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 

 are broadly cordate, and they give the impression of being mounted fairly and 

 squarely upon the stem by means of the highly swollen and notched basal portion. 

 But it is only necessary to detach one of the scales from the stem to convince 

 oneself that this is not the case, and that the part taken at fii-st sight to be the 



