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Show 408 UTRICULARIA NEGLECTA. CHAP. XVII. spread analogy, this would have re~dered them ~ore t; nsitive to irritation, or would by Itself ha~e excited. 1novmnent ; but no effect was produced. We may, therefore, conclude that animals enter merely by forcing their way through the slit-like orific.e; their heads serving as a wedge. But I am surpnseu that such sinall and weak creatures as arc often captured (for instance, the nauplius of a crustacean, and a tarcligrad ) should be strong enough to ac~ in this Inanncr, seeing that it was difficult to push In one enu- of a Lit of a hair t of an inch in length. N everthelcss, it is certain that weak and sinall creatures do enter, and Mrs. Treat, of New Jersey, has been more successful than any other observer, and has often witnessed in the case of Utricularia clandestina the whole process.* She saw a tardigrade slowly walking round a bladder, as if reconnoitring ; at last it crawled into the depression where the valve lies, and then easily entered. She also witnessed the ontrapn1ont of various minute crustaceans. Cypris '~was " quite wary, but nevertheless was often caught. " Coming to the entrance of a bladder, it would some" times pause a moment, and then dash away; at " other times it would come close up, and even ven" ture part of the way into the entrance and back out " as if afraid. Another, 1nore heeuless, would open " the door and walk in ; but it was no sooner in than " it manifested alarm, drew in its feet and antennre, and closed its shell." Larvre, apparently of gnats, when " feeding near the en trance, are pretty certain " to run their heads into the net, whence there is no " retreat. A large larva is sometimes three or four " hours in being swallowed, the process bringing to t< 'New York Tribune,' reprinted in the' Gard. Chron.' 1875, p. 303. CHAP. XVII. MANNER OF CAPTURING PREY. 409 " mind what I have witnessed when a small snak " makes a large frog its victim." But as the va1v does not appear to be in the least irritable th slow swallowing process must be the effect of' the onward movement of the larva. It is difficult to conjecture what can attract so many crea,tures, animal- and vegetable-feeding crustaceans, worn1s, tardigrades, and various larvre, to on ter the bladders. Mrs. Treat says that the larvre just referred to are vegetable-feeders, and seem to have a special liking for the long bristles round the valve, but this taste will not account for the entrance of animalfeeding crustaceans. Perhaps small aquatic animals habitually try to enter every small crevice, like that between the valve and collar, in search of food or protection. It is not probable that the remarkable transparency of the valve is an accidental circumstance, and the spot of light thus formed may serve as a guide. The long bristles round the entrance apparently serve for the same purpose. I believe that this is the case, because the bladders of some epiphytic and marsh species of Utricularia which live embedded either in entangled vegetation or in mud, have no bristles round the entrance, and these under such conditions would be of no service as a guide. Nevertheless, with these epiphytic and marsh species, two pairs of bristles project frmn the surface of the valve, as in the aquatic species ; and their use probably is to prevent too large animals from trying to force an entrance into the bladder, thus rupturing the orifice. As under favourable circumstances most of the bladders succeed in securing prey, in one case as many as ten crustaceans ;-as the valve is so well fitted to |