268 H. \\ . HKC.NKR. 



2. Living protozoa of various kinds were found in the bladders; 

 these were principally euglenas, hut a few other flagellates, 

 minute ciliates, and amoebae were encountered. 



3. Animals do not force their way into the bladders as hitherto 

 supposed but are captured as follows: the normal bladder has 

 compressed side walls; organisms enter the vestibule and by 

 their movements stimulate the valve to open; water rushes in 

 as the side walls expand and sucks in with it the stimulating 

 organism; then the valve closes and the organism is unable to 

 escape. 



4. \Yhen a bladder expands its contents are increased approxi- 

 mately 88 per cent, by the outside medium which is sucked in 

 with the prey. 



5. Bladders expand when the wall is punctured and when the 

 mouth opening is laterally or antero-posteriorly compressed. 



6. Expanded bladders recover their compressed condition and 

 are "set" for another capture in about 20 minutes. How 88 

 per cent, of their contents pass out during the period of com- 

 pression is not known. 



7. Euglenas occur frequently in bladders in nature but plants 

 loose their infection if kept for many months in the laboratory. 

 Free-living euglenas are captured by bladders and live and 

 multiply within. They are not injured in bladders that have 

 recently captured and killed paramecia. The euglenas that 

 inhabit bladders in nature are probably captured free-living 

 species and not species peculiar to the utricularia plant. 



8. Paramecia are captured by bladders that are either attached 

 to or detached from the plant; about 30 per cent, of bladders 

 immersed in paramecium cultures succeeded in capturing one or 

 more specimens within an hour. The number of paramecia 

 captured by the bladders depends upon the culture medium only 

 in so far as this affects the rate of swimming of the organisms and 

 hence their chances of coming in contact with the valve of the 

 bladders. Paramecia die within the bladders in an average 

 period of about 75 minutes; some of them lived for many hours 

 and some that were introduced into bladders with a fine pipette 

 lived for 17 days. Paramecia (lit- usually within several hours 

 in bladders previously thoroughly cleaned out by irrigation. 



