194 



practically under xerophytic conditions. This would tend to 

 render the root system inefficient as a means of water absorption 

 and make the possession of a water-storing organ like the pitch- 

 ered leaf of great advantage to the plant. 



The epiphyte Nepenthes represents the highest degree of adap- 

 tation, in that it produces a protein-dissolving enzyme, the nepen- 

 thin of Vines (Ann. Bot. 15: 563. 1901). Even here, how- 

 ever, the absorption of protein by the leaves is not absolutely 

 essential to the life of the plant, though of great advantage. 

 Nepenthes, then, stands at the upper limit in the evolution of 

 plants with pitchered leaves, while Sarraceiiia purpurea is near 

 the lower limit. Between them are numerous forms with vary- 

 ing degrees of adaptation. 



New York Botanical Garden. 



