PROTOZOA AND THE UTRICLES OF UTRICULARIA. 245 



instantly." This describes only in part the method of capture. 

 The solution of the problem was reached when a compressed 

 bladder whose valve was touched with a needle at the lower, free 

 edge suddenly became distended by an inrush of water. A 

 similar reaction occurred in every compressed bladder similarly 

 treated, but no change was evident when the valve of a distended 

 bladder was touched with a needle. Several experiments were 

 carried out to test the capacity of bladders to recover their 

 compressed condition after being distended by the touch of a 

 needle. 



Experiment M. 15. Five branches were selected and a number of bladders on 

 each were distended by touching the lower part of the valve with a needle: branch 

 a, 7 bladders; b, 4; c, 4; d, 4; e, 4. Forty minutes later these bladders had all 

 regained a compressed condition. Several of them contained large insect larvae 

 and many of them crustaceans in various stages of decay, but apparently the 

 previous capture of food had no influence on their assumption of the compressed 

 state. These bladders were all again distended as before. When reexamined in 

 20 minutes all bladders on branches a, b and c were found to be compressed and on 

 each of branches c and d, 2 were completely and two partially compressed. They 

 were all again distended. Ten minutes later none of the bladders had entirely 

 recovered. Fifteen minutes later some had entirely recovered, some almost and 

 others only slightly. At this time the bladders were all again distended. Two 

 hours and 15 minutes later all bladders on branches a, b, and c had recovered and 

 became distended when touched with a needle, but only 2 on each of branches c 

 and d were compressed. Two hours and 45 minutes later all bladders on branches 

 a, b, and c had recovered except 2 on each which had only partly recovered; none 

 recovered on branch c; and 2 recovered on branch d. All bladders that were 

 entirely or partly compressed were distended with a needle at this time. Seventeen 

 hours later or 24 hours after the beginning of the experiment, on branch a, 4 bladders 

 had entirely recovered and 3 had partly recovered but became fully distended 

 when touched with a needle; on branch b, 2 had entirely recovered and 2 had 

 partly recovered, all became distended when stimulated; on branch c, 2 had entirely 

 recovered, one had partly recovered and one was not compressed at all; on branch 

 d, none of the experimental bladders had recovered, and it was noted that all the 

 other bladders on this branch were distended, due possibly to some change in the 

 physiological condition of the branch; on branch e, one partly recovered, the other 

 three were fully distended. 



This experiment gives some idea of the rapidity with which the 

 bladders may capture their prey. The length of time from the 

 capture of an organism until the trap is set for another is ap- 

 parently about 20 minutes, and it is evident that the capture of 

 organisms may occur a number of times in one day. The failure 

 of some of the bladders to regain the compressed condition after 



