250 K. W. HEGXER. 



As already noted, a distended bladder regains its compressed 

 condition in about 20 minutes. How this is accomplished by the 

 plant I do not know but it involves the absorption by or expulsion 

 from the bladder of about 88 per cent, of its liquid contents. 

 Several experiments were performed in an attempt to determine 

 whether liquid passes into and out of the bladders at any time 

 except when organisms are captured. 



Experiment 66. Seven branches bearing from 6 to 19 bladders each were 

 immersed for 2\ hours in aqueous solutions of carmine, india ink, eosin, safranin, 

 and crystal violet. All bladders were deeply stained in safranin and crystal violet. 

 The walls were not stained in the other solutions but many of the bladders contained 

 the coloring matter; 4 of 9 bladders in carmine contained red granules; 8 of 14 

 in eosin were filled with this solution; and 10 of 15 took in India ink. 



Experiment 67. Branches bearing 100 bladders were immersed in an aqueous 

 solution of eosin for 3 hours. The solution was found within 69 of these bladders 

 at the end of this period, mostly in young and medium sized specimens. 



Experiment 68. Branches bearing 52 bladders were immersed in a paramecium 

 culture for 2 hours and then in an eosin solution for 2\ hours. Paramecia were 

 captured by 12 bladders and became stained with eosin in n of them. Nine of 

 the bladders that did not capture paramecia took in eosin and 32 did not. 



Experiment 6g. Nine branches bearing 79 bladders were immersed in a para- 

 mecium culture 2 hours and then in an eosin solution 2 hours. Paramecia were 

 captured by 67 bladders and became stained with eosin in 65 of them. The 12 

 bladders that did not capture paramecia all took in eosin. 



Experiment M. 20. Compressed bladders were placed in an eosin solution and 

 expanded thus adding this solution to their contents. They were then washed in 

 water, placed in hollow ground slides and examined. None of these bladders 

 recovered the compressed condition. 



These experiments prove that solutions of eosin, carmine and 

 India ink are taken in by bladders that have not captured 

 paramecia and eosin solution by bladders that have captured 

 paramecia. That this is due to spontaneous expansion of the 

 bladders is possible but not probable. How the solutions were 

 taken in is still in doubt. This is true also regarding the passage 

 of liquid out of the bladders. This is a problem for the plant 

 physiologists to solve, and work on it is now in progress. 



After discussing the probable function of the glands located 

 around the exterior of the entrance Darwin concludes that these 

 "are adapted to absorb matter from the putrid water, which will 

 occasionally escape from bladders including decayed animals." 

 He remarks, however, that, "The valve fits so closely, judging 

 from the result of immersing uninjured bladders in various 



