THE PROTOZOA OF THE PITCHER PLANT, 

 SARRACENIA PURPUREA. 1 



R. \V. HEC.NER. 



Investigations of protozoa within the bladders of utricularia 

 plants led the writer (Hegner, 1926) to examine the literature on 

 other insectivorous plants and to carry out the experiments de- 

 scribed below. The general problem under attack is that of 

 host-parasite relationships and the specific problem is that of the 

 relations between intestinal protozoa and their environment. 

 Primitive conditions of digestion might be expected in insec- 

 tivorous plants and this idea is responsible for the present 

 investigation. Whether or not the liquid in the pitchers of the 

 pitcher plants contains digestive enzymes secreted by the plant, 

 which digest insects and other animals that enter the pitcher, 

 is a problem that has been carefully studied by many investigators 

 for many years. On several occasions when the problem seemed 

 to be solved, a new factor was suggested that made it necessary 

 to carry on further investigations. Among the most recent 

 papers is that of Hepburn (1922) who concludes "on both 

 morphological and bio-chemical grounds, that the pitchers of 

 most, if not all, species of pitcher plants are designed for the 

 capture and digestion of prey as a means of nutrition for the 

 plant" (page 776). Among the species studied by Hepburn, 

 St. John and Jones (1920) was Sarracenia pur pur ea and pro- 

 teolytic enzymes (proteases) were found in the pitcher liquid of 

 this species. Many types of experiments have been used to 

 determine the character of the pitcher liquid but no one seems 

 to have employed protozoa as indicators. 



That living protozoa occur in the pitcher liquid of various 

 species of pitcher plants has been mentioned by several investi- 

 gators but only one worker (van Oye, 1921) has made a careful 

 study of the species. In the pitcher liquid of Nepenthes melam- 



1 From the Department of Medical Zoology, School of Hygiene and Public 

 Health, The Johns Hopkins University, and the Mt. Desert Island Biological 

 Station, Salisbury Cove, Maine. 



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