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 
organie 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 affected; 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. 
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 (Lathrea 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 elastie appearance, and are covered throughout their entire length 
with thick squamous leaves placed closely one above the other (see fig. 257 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 first sight to be the 
