216 



BOTANY 



at the same time. The absorption of the disorganised animal remains seems to be 

 performed by forked hairs which spring from the walls of the bladder. 



More remarkable still, and even better adapted for its purpose, is the mechanism 

 exhibited by other and now well-known insectivorous plants. In the case of 

 Venus Fly-trap [Dionaea), growing in the peat bogs of 

 North Carolina, the capture of insects is effected by 

 the sudden closing together of the two halves of the 

 leaves (Fig. 189). This action is especially due to 

 the irritability of three bristles on the upper side of 

 each half-leaf (the leaf surfaces themselves are much 

 less sensitive). Upon the death of the insect caught 

 by the leaf, a copious excretion of digestive sap 

 takes place from glandular hairs on the leaf surface, 

 followed by the absorption of the products of the 

 digestive solution. In the case of other well-known 

 insectivorous plants (Nepenthes, Oephalotus, Sarra- 

 cenia, Darlingtonia), the traps for the capture of 

 animal food are formed by the leaves which grow in 

 the shape of pitchers (Figs. 33, 190). These trap- 

 like receptacles are partially filled with a watery fluid 

 excreted from glands on their inner surfaces. En- 

 ticed by secretions of honey to the rim of the pitcher 

 (in the case of Nepenthes), and then slipping on the 

 extraordinarily smooth surface below the margin, or 

 guided by the downward-directed hairs, insects and 

 other small animals finally fall into the fluid and 

 are there digested by the action of ferments and 

 acids. In Sarracenia and Oephalotus, Goebel was 

 unable to discover any digestive ferments ; but in 

 Oephalotus, however, it was possible to determine 

 -Pitchered leaf of a that the secretions have antiseptic properties. The 

 Nepenthes A portion of the M . like appendage at the opening of the pitcher of 



13/E61&1 W3.ll 01 til 6 pitcii6r lliiS , _, , . _ 



been removed in order to Nepenthes, Sarracenia, and Oephalotus does not shut ; 

 show the fluid (f), excreted by its function seems to be merely to prevent foreign 

 the leaf-glands. (Reduced.) substances from falling into the pitcher, and parti- 

 cularly to keep out the rain. The entrance to the 



tubular leaves of Darlingtonia is under the helmet-like extremity, and therefore 



a lid is unnecessary. 



Fig. 190.- 



III. Respiration 



It is a matter of common knowledge that animals are unable to 

 exist without breathing. In the higher animals the process of respira- 

 tion is so evident as not easily to escape notice, but the fact that 

 plants breathe is not at once so apparent. Just as the method of the 

 nutrition of green plants was only discovered by experiment, so it also 

 required carefully conducted experimental investigation to demon- 

 strate that PLANTS ALSO MUST BREATHE IN ORDER TO LIVE ; that, like 



animals, they take up oxygen and give off carbonic acid. Even 

 Liebig in 1840, in his epoch-making work (Die wganische Chemie in 



