196 



VEGETABLE PHYSIOLOGY 



the higher animals, by the instrumentality of which the 

 insoluble proteins of their prey are converted into pep- 

 tones, and possibly partially into ammo- and amido-acids, 



prior to actual absorption. 

 Among these Nepenthes may 

 be mentioned. 



The pitchers of Nepenthes 

 (tig. 94) are in the main 

 similar to those of Sarra- 

 cenia. They possess means of 

 attracting insects to them, of 

 seducing them into the in- 

 terior of the pitcher, and of 

 preventing their subsequent 

 escape, all of which are com- 

 parable to those already de- 

 scribed. The pitchers con- 

 tain a watery liquid, which 

 is secreted by their interior 

 surfaces, and which has a 

 faintly acid reaction. When 

 an animal is captured and 

 falls into the liquid, it sets 

 up a further secretion, which 

 is more strongly acid, and 

 which contains a peculiar 

 body known as an enzyme 

 or ferment, the properties of 

 which will be discussed in a 

 subsequent chapter. This 



ferment somewhat closely resembles the active principles of 

 the gastric and pancreatic juices of the human body, and in 

 the acid medium is capable of converting the proteins of the 

 prey into peptone, leucin, and tyrosin, products which are 

 all soluble and diffusible. This secretion is prepared by 

 special glands, which are plentifully distributed over the 

 lower portion of the internal face of the pitcher. 



FIG. 94. MODIFIED LEAF (PITCHER) 

 OF Nepenthes. (After Kerner.) 



