THE PITCHER LIQUOR OF NEPENTHES. 129 



These experiments indicate that in Sarracenia, as in Nepenthes, 

 the protease of the pitcher liquor plays the leading role in the 

 digestion of the captured insects. The bacteria of the pitcher liquor 

 have merely a minor role ; they live in symbiosis with the Sarra- 

 cenia plant, draw their food from the digested insects, and assist 

 to a limited degree in the digestion of these insects. Tissue en- 

 zymes of the insects doubtless also participate in the process of 

 digestion. 



The author desires to record his deep indebtedness to Dr. John 

 M. MacFarlane, director of the botanic garden and laboratory of 

 this university, for the material and facilities placed at his disposal 

 for the prosecution of this research, during 1914-1916. 



Botanical Laboratory, 



University of Pennsylvania. 



