Francis E. Lloyd — 252 — Carnivorous Plants 



be drawn in. Mr. J. H. Buzacott writes me that this has been ob- 

 served at Meringa, Queensland, {20 — 11) where tadpoles of Bnfo nia- 

 ritius, imported to control insect pests in sugar cane, have been 

 destroyed in numbers. 



On the sucking-in of prey: — The fact that large prey (young 

 tadpoles and fish fry, worms etc.) can be caught by some part of the 

 body, usually the tail, has long been known. After a tadpolette has 

 been trapped but not completely engulfed, it has been stated that the 

 body is later sucked in. This would obviously be limited by the 

 volume of the trap. The question has been raised by me, does this 

 sucking-in actually occur and if so what is the mechanical procedure? 

 I have recently taken pains to get evidence on this point. I employed 

 Utriciilaria aff. gibba, sent me from Pasadena, Calif., by Dr. F. Went. 



In a series of experiments young mosquito larvae about 2 mm. long 

 were used. By manipulation it was possible to get one caught by the 

 tail, the head being too big to enter the trap. When this occurred, 

 one half of the body was instantaneously engulfed, leaving four or five 

 joints behind the thorax projecting beyond the mouth of the trap. 

 The joints served as clear-cut measures. Several cases were observed, 

 and all followed the same pattern. One example will suffice. The 

 larva was caught by the tail, the door clamping down between the 

 sixth and seventh joints, while six remained protruding (11:30 hrs.). 

 At 18 hrs. only the thorax and head remained protruding. Next 

 morning, the thorax had also been engulfed, the head only, too big to 

 enter, being left outside. (Text fig. 8, A, B). Since the body of the 

 larva prevents the door from assuming its normal set posture, and 

 though the trap walls did not become concave, as observed from time to 

 time, it must be inferred that nevertheless the entrance was sufficiently 

 occluded by the door and larva so that the exhaustion of the water 

 from the inside of the trap could proceed, creating a suction on the 

 prey from time to time, and drawing it gradually in. As I did not see 

 this happening during a prolonged period of observation, I cast about for 

 more suitable experimental material. This I found in fine shreds of 

 albumin, made by stirring egg-white in boiHng water. These were soft 

 and of fairly even caliber. Of a goodly number of experiments I choose 

 the following. Case i (Text fig. 8 C, D). A shred about two milli- 

 meters long was presented to the trap by touching the tripping bristles 

 with its end. One half of the shred was swallowed; the rest remained 

 protruding. On this some bits of rust, detached from the needle point, 

 adhered, serving as marks. When examined 18 minutes later, the entire 

 shred had been taken in. In the meantime the experiment was re- 

 peated (Case 2) (Text fig. 8 E-H) and kept under close and continuous 

 observation. Immediately after the door had clamped down on the 

 partially engulfed shred, the latter was seen to sHde slowly in for two 

 minutes, when it stopped (F). This movement was the result of 

 residual wall action. Nothing further happened for about ten minutes 

 (during which time a partial reduction of pressure within the trap took 

 place) when the door opened and closed rather slowly (the movement 

 was quite visible to the eye) and another portion of the shred entered 

 (11 43 hrs.). By 16:00 hrs. the shred had been entiredly swallowed (H). 

 The walls were now concave, and the trap, completely reset, reacted 



