262 R. W. HEGXER. 



the data available there appears to be no striking difference 

 between bladders that have been inoculated with paramecia, 

 attached or detached, irrigated or not irrigated. 



Paramecia are captured more frequently by older, larger bladders 

 than by younger, smaller bladders. In some of the earlier experi- 

 ments the younger, smaller bladders seemed to become more 

 readily infected with paramecia than those older and larger. 

 Three experiments were carried out to test this. Branches 

 bearing both young and old bladders were selected and the 

 sections with the young and those with the old bladders cut out 

 and placed in different paramecia cultures for 2 hours. 



Experiment 39. Three of 48 young and 6 of 48 old bladders 

 became infected. 



Experiment 40. Eight of 30 young and 17 of 30 old bladders 

 became infected. 



Experiment 43 . Thirteen of 30 young and 1 1 of 30 old bladders 

 became infected. 



A total of 24 young and 34 old bladders became infected in 

 these experiments. This is probably too small a number to be 

 significant, but could be explained by the greater chance the 

 older bladders offer because of the larger size of the entrance. 



Paramecia do not die in a short time in old dead bladders or in 

 mature bladders that have been killed by heat. When bladders 

 become very old they loose their chlorophyll, become detached 

 from the branches and fall to the bottom. Two experiments 

 were carried out to determine whether paramecia are captured 

 by these old, dead bladders. 



Experiment 49. Forty old bladders were placed in a paramecium culture for 

 2 hours. Seven of them captured specimens; none of these died and all had 

 escaped within 24 hours, indicating that they had entered through openings in 

 the walls of the bladders. 



Experiment 65. Sixty old bladders were similarly tested. No paramecia were 

 captured. 



Two experiments were carried out with mature bladders which 

 were killed by being subjected to boiling water for 2 minutes. 



Experiment 59. Seven branches bearing 68 bladders were immersed in a para- 

 mecium culture for ij hours. All bladders were negative. 



Experiment 61, Nineteen bladders on 5 branches were inoculated with para- 

 mecia and kept under continuous observation for 2-J- hours. None died. Twenty- 

 four hours later many had escaped. 



