Chapter IV —73— Nepenthes 



The larvae of Apogonia spherica were found entire but quite digested 

 internally. Insects die in the pitcher fluid much more quickly than in 

 distilled water. In 48 hours or so, insects are disintegrated, only their 

 chitinous skeletons remaining. Such statements, encountered in other 

 writings, indicate a very vigorous action. Goebel ventured the state- 

 ment that of all the pitchered carnivorous plants Nepenthes is the most 

 vigorous in these matters. 



Clautriau (i 899-1 900) took the opportunity of studying Nepen- 

 thes in its habitat in Java. His results fully corroborate in general 

 Goebel and Vines. He observes: 



While the fluid in unstimulated pitchers is neutral, it becomes acid 

 on the introduction of foreign bodies. Even shaking has this effect, 

 the strongest acidity obtained being equal to that of a Uter of water 

 acidified with 2 cc. of fuming HCl. In the fluid there is a thermolabile 

 substance which acts as a wetting agent, so that insects are quickly 

 drowned but are not killed by any poison. Insects are digested with- 

 out any putrefaction. Antiseptics such as formaldehyde, chloroform, 

 etc. inhibit both the secretion of acid and digestion, and the pitchers 

 presently die. On the introduction of egg-white, both digestion and 

 absorption occurred. If a small quantity was used absorption equalled 

 digestion in rate; if a too large quantity was used, the products re- 

 mained in quantity sufficient to afford a culture medium for bacteria. 

 Quantitative experiments showed that 5 cc. of egg-white (10 cc. to 90 

 cc. water) is completely digested in vigorous pitchers in 2 days. If a 

 pitcher were separated from the plant, digestion was inhibited, and 

 Clautriau usually found that in vitro experiments gave negative re- 

 sults. At home in Brussels he showed by refined methods that al- 

 bumin is completely digested to peptone. This is readily absorbed by 

 the pitcher walls, so that he was able to give successive doses of food 

 (albumin) and see that they were digested perfectly by the pitchers of 

 N. M aster siana. 



Clautriau concluded that the enzyme is a true pepsin as it acts 

 only in an acid medium and produces true peptone as an end result. 

 No other products could be found. No amylase was detected. The 

 evidence indicated that an ample secretion of both enzyme and acids 

 required stimulation, and, on microchemical evidence, that peptone is 

 absorbed by the glands and stored as protein. A superabundance of 

 food may allow the play of bacteria, and the products of their activity 

 (amino acids and ammonia) may be used by the plant. These do not 

 necessarily damage the pitcher itself. 



Fenner has (1904) advanced an interesting presentation of what 

 he believes goes on in natural conditions. The original pitcher fluid is 

 slightly acid (formic acid, Goebel). If a few gnats are introduced, 

 they float on top of the fluid. If alive they endeavor to escape by 

 cKmbing up the wall, and in this way they come in contact with the 

 glands below their overhanging eaves, which, Haberlandt has sug- 

 gested, serve the purpose of retaining fluid by capillarity. ^ The body 

 of an insect wet with pitcher fluid thus applied serves to stimulate the 

 glands to action, when they secrete a highly viscid, active fluid which 

 attacks the insect so vigorously that it is digested in 5-8 hours. 

 Tenner tested this view experimentally by taking an opened pitcher 



