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bladders being filled with gas, buoy up the^plant to the surface 

 during the flowering season, after which the whole plant sinks 

 to the bottom until the same thing is repeated in the following 

 year. Darwin believes this to be a fallacy, and that the only 

 purpose of the bladders is to capture minute animals which serve 

 to nourish the plant, which according to this authority has no root, 

 but floats loosely in the water. The bladders are furnished 

 internally with glands. These glands do not discharge anything, 

 but are for absorption. The entrance to the bladder is by a valve 

 that opens inwards, and there is a collar against which it rests, and so 

 prevents the valve opening outwardly, so that a small water flea or 

 minute animal can push open the valve and enter, but having 

 once entered, escape is impossible. Into this living trap the small 

 animals force themselves, and as they can never escape they die 

 in prison. The soft parts of the dead animal are then absorbed 

 by the plant, and the hard insoluble parts rejected. On the few 

 occasions on which I examined the bladders I found all tenanted, 

 but the animals (one being in each bladder) seemed active arid 

 full of life. According to Darwin they might continue in that 

 state until they died from want of air and food. Darwin says, 

 with respect to the entrance into the bladders : " Animals 

 enter the bladders by bending inwards the posterior free 

 edge of the valve, which, from being highly elastic, shuts 

 again instantly. As the edge is extremely thin and fits 

 closely against the edge of the collar, both projecting into the 

 bladder, it would evidently be very difficult for any animal to get 

 out when once imprisoned, and apparently they never do escape. 

 To show how closely the edge fits, I may mention that my son 

 found a daphnia which had inserted one of its antennse into the 

 slit, and it was thus held fast during a whole day. On three or 

 four occasions I have seen long narrow larvae, both dead and alive, 

 wedged between the corner of the valve and collar, with half their 

 bodies mthin the bladder, and half out." Darwin felt much 

 difficulty in understanding how such weak and minute animals 

 could find their way into the bladders ; but he found that a thin 

 human hair, when cut short, could be made to enter, and that 



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