BIOCHEMICAL STUDIES OF INSECTIVOROQS PLANTS' 



CONTENTS 



Page 

 I. The Work of Pre\aous Investigators on Nepenthes, by Joseph Samuel Hep- 

 burn, A.M., M.S., Ph.D 419 



II. A Study of the Protease of the Pitcher Liquor of Nepenthes, by Joseph 



Samuel Hepburn, A.M., M.S., Ph.D 442 



III. A Bacteriological Study of the Pitcher Liquor of Nepenthes, by Joseph S. 



Hepburn, Ph.D., and E. Quintard St. John, M.D 451 



W. Occurrence of Antiproteases in the Larvae of the Sarcophaga Associates of 



Sarracenia Jlava, by Joseph Samuel Hepburn and Frank Morton Jones 460 



I. The Work of Previous Investigators on Nepenthes 



BY 



Joseph Samuel Hepburn, A.M., M.S., Ph.D. 



Voelcker (1) studied the composition of the pitcher Hquor of Nepen- 

 thes. He describes the Hquor from unopened pitchers as a clear, colorless 

 liquid with a refreshing taste, an agreeable but not very pronounced 

 odor, and an acid reaction to litnfus. The acid was not volatiUzed by 

 evaporation of the liquor to dryness. 



The total soUds of the liquor were determined by drying at 212° F. 

 (100° C), the ash by ignition of the soUds at a red heat. Total solids 

 are expressed as percent of the pitcher liquor, ash and volatile matter 

 as percent of the total soUds. The solids were yellow or cream colored, 

 very hygroscopic, and readily soluble in water. Samples of Uquor from 

 different unopened pitchers gave the following values: — 



Total Volatile matter Ash 



solids (loss on ignition) 



1. 0.92 



2. 0.91 25.86 74.14 



3. 0.62 36.06 63.94 



4. 0.27 32.92 67.08 



* Through the kindness of Dr. John M. Macfarlane, these studies were conducted 

 in the Botanical Laboratory and Nepenthes House of the University of Pennsylvania 

 during 1914-1916. Papers that have appeared since that time have also been cited 

 in the bibliographies. 



