PROTOZOA AND THE UTRICLES OF UTRICULARIA. 269 



Paramecia usually break up into granules within several hours 

 after capture. Paramecia are not killed in old dead bladders 

 nor in mature bladders killed by heat. 



9. Specimens of the shelled rhizopod, Centropyxis aculeata, 

 may be captured by bladders; they are not directly killed but 

 die slowly of starvation. 



10. The green flagellate, Heteronema acus, is captured but not 

 injured by the bladders. Phacus longicaudus , is captured by 

 bladders but not injured; it may multiply within the bladders. 

 Bladders capture Chilomonas paramecium. 



1 1 . The ciliate, Stentor polymorphus, is captured and killed by 

 bladders as is also Stylonychia pustulata. Colpidium colpoda is 

 captured but may live for a day or more. 



12. Material from the intestine of tadpoles containing flagel- 

 lates was introduced into bladders, but the bladders were quickly 

 killed. 



13. Nematodes and rotifers captured by bladders live for 

 many hours within. 



Conclusions. The principal conclusions from these studies are, 

 (i) organisms do not force their way into bladders but are 

 captured by them; (2) the bladders do not select their prey but 

 any organism small enough to enter the vestibule may be cap- 

 tured; (3) organisms as small as Chilomonas paramecium (24 

 microns in length) may be captured; (4) the protozoa found in 

 the bladders are not intruders but captives and are probably all 

 free-living species; and (5) some of the captured protozoa live 

 successfully within (Euglena, Heteronema, Phacus), some slowly 

 starve to death (Centropyxis) and others are more or less quickly 

 killed and digested (Paramecium, Stentor, Stylonychia, Colpidium). 

 The data presented indicate that the bladders secrete something 

 that kills and digests paramecia but does not injure euglenas. 

 The origin and character of this secretion and the changes in 

 the plant during the compression and expansion of the bladders 

 are problems for the plant physiologist to solve. 



LITERATURE. 

 Brumpt, . 



'25 Capture dcs larves cle culicides par les plantes du genre Utricularia. Ann. 

 Parasit., 3: 403-411. 



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