258 R. W. HEGXER. 



are combined the average active period after capture is found to 

 be 69 minutes. The average period until death in the same 

 experiments was 75 minutes for 9 specimens; 72 minutes for 23; 

 and 93 minutes for 62. When the data of the experiments are 

 combined the average period of the 94 spcimeens studied is 

 found to be 85 minutes. It may be concluded that the actual 

 death period lies between that when the specimens were last 

 observed alive and that when they were first observed to be 

 dead, which is on the average between 69 and 85 minutes. 

 Seventy-five minutes may, therefore, be selected as approxi- 

 mately the length of time paramecia, on an average, remain 

 alive after being captured by the bladders of utricularia. 



When injected into attached bladders paramecia may die within 

 a short period or remain alive for many days. In three experiments 

 paramecia were injected with a fine pipette into bladders attached 

 to branches of the utricularia plant. 



Experiment 13. Paramecia were injected into 6 bladders attached to one stem, 

 from 2 to 10 specimens in each bladder. All -were alive at the end of 2\ hours, 

 but were dead in 3 of the bladders at the end of 26 hours. The paramecia remained 

 alive in one bladder for 6 days and escaped probably because of the disintegration 

 of the wall of the bladder. In another bladder two of the original 5 paramecia 

 were still alive on the i6th day, but were very sluggish and quite transparent being 

 evidently in a starved condition. One of these became abnormal in shape during its 

 confinement; this specimen was still present after 17 days but was gone (escaped?) 

 on the 1 8th day. 



Experiment 52. Nineteen bladders attached to 6 branches were injected with 

 from one to n paramecia each. In three bladders the organisms died within 26 

 67 and 74 minutes respectively. In the other 16 bladders all the specimens re- 

 mained alive at least 2 hours and in some of these the paramecia lived lor 4, 5, 6 

 or 7 days. 



Experiment 57. Fifty-three bladders attached to 7 stems were injected with 

 from one to 20 paramecia each. They were killed in 32 of the bladders within 

 4 hours as follows: in 3 bladders in 25, 51 and 55 minutes respectively; in 8 bladders 

 within from one to 2 hours; in n bladders in from 2 to 3 hours; and in 10 bladders 

 in from 3 to 4 hours. The paramecia disappeared (escaped?) from 5 bladders 

 within 24 hours, but remained active in the remaining 16 bladders at least one day, 

 and in 3 of them 2 days, in 3 of them 3 days, and in one of them 5 days. 



When the results of these injection experiments are compared 

 with those described in which the paramecia were captured by 

 the bladders the most noticeable difference is the greater length 

 of time required for the death of most of the organisms, extending 

 as in Exp. 13 to a period of 17 days. This suggests that many 



