THE INTERRELATIONS OF PROTOZOA AND THE 

 UTRICLES OF UTRICULARIA. 1 



R. \V. HEGNER. 



References to the presence of "Infusoria" within the utricles of 

 Utricularia occur in several publications on insectivorous plants, 

 but no one has hitherto studied the interrelations of these 

 protozoa and the plants. The situation suggests various ques- 

 tions, such as (i) are the protozoa intruders that act as scavengers 

 feeding on the dead bodies of other captives; (2) are they 

 captured by the plants and used as food ; (3) are they adventitious 

 residents that slowly starve to death within their prison-like 

 walls; or (4) are they "normal" inhabitants, possibly differing in 



FIG. i. Part of a branch of Utricularia showing bladders. X 4. 



species from free-living protozoa, that maintain more or less 

 intimate parasitic or symbiotic relations with the utricles. If 

 the last named possibility is correct these protozoa may be 

 thought of as living within a sort of primitive plant stomach 

 the liquid contents of which consist of digestive ferments and a 

 certain quantity of organic materials in various stages of diges- 



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

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

 Salisbury Cove, Maine. The writer is indebted to Mrs. Ethel Norris Rask for 

 making the drawings. 



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