PROTOZOA AND THE UTRICLES OF UTRICULARIA. 263 



No differences in the behavior of paramecia were noted when 

 placed in liquid from non-infected and infected bladders. Eleven 

 experiments were carried out to determine whether any differences 

 as regards the effect upon paramecium could be detected between 

 the liquid from unfed bladders and that from bladders that had 

 recently captured and killed paramecia. Liquid from the latter, 

 as noted above (p. 254) has no effect on euglenas added to it. 



Experiments 31, M. 8, M. Q, M. 14. In these experiments the liquid from 107 

 bladders that had not captured paramecia was either squeezed out or withdrawn 

 with a fine pipette, and either placed in a hollow ground slide in a moist chamber 

 or treated as a hanging drop. Several paramecia were added to each and the 

 preparations examined at frequent intervals. In Experiments M. 8 and M. 14 the 

 paramecia were normally active at the end of 48 hours when the experiments were 

 discontinued; in the other experiments the paramecia lived at least s| hours and 

 death was later due to drying or to insufficient medium. 



Experiments 26, 32, 60, M. 10 and M. 16. Liquid from 203 control bladders and 

 from 203 bladders that had killed paramecia was squeezed out or withdrawn with 

 a fine pipette and its effects on paramecia tested. No significant difference was 

 noted between the behavior of the paramecia in the liquid from non-infected 

 bladders and in that from infected bladders. When a small amount of liquid was 

 used the paramecia died in all cases within a few hours; when a larger amount was 

 used no change was noted within 48 hours and the experiments were therefore 

 discontinued. 



The results of the experiments on paramecia described above 

 are conclusive so far as they concern the effects of their capture 

 or injection into the bladders under various conditions. Just 

 how the results noted are brought about has not been determined 

 and evidently will require for its solution extended experimental 

 research. Among the questions that arise are the following: 



What differences are responsible for the death of certain 

 protozoa such as paramecium and stentor (see below) and the 

 apparent ability of others such as euglena, heteronema, and 

 phacus to live indefinitely within the bladders? (see below). 



What is responsible for the rapid death of paramecia in certain 

 bladders and their ability to live for many days in others? 



Does the plant, when in a certain physiological state, secrete 

 something into the bladder that brings about the death of 

 paramecia? 



Why do some paramecia disintegrate almost immediately and 

 others from several hours to several days after death? 



When several paramecia are confined in a single bladder, why 

 do some disintegrate before others, as sometimes happens? 



