Francis E. Lloyd — 6 — Carnivorous Plants 



conviction that its structure also is adapted for the capture of small 

 insects". 



Contributory structural features of these traps are the glands, phys- 

 iologically of two kinds, but of identical {Dionaea) or different (Aldro- 

 vanda) structure, and the sensitive hairs, which are local points of 

 greater sensitivity. The latter only are unique in structure. There is 

 also motile tissue which, startling in rapidity though its movements 

 are, appears to work in much the same way as that of tissues exhibit- 

 ing geotropic responses, according to Brown. But should Caltha 

 dioneaefolia, as Delpino suggested, turn out to be quite parallel to 

 Dionaea, it would only add another member to a very small unique 

 group. 



A curious case of an insect-catching grass, Molinia coerulea, briefly 

 described by F. Ludwig in 1881, may here be indicated as an analog, 

 albeit a very loose one, to the trap of Dionaea. It appears that this 

 grass can catch small insects between its paleae, which act as the jaws 

 of a spring trap, after the fashion of a 5-cent spring mousetrap. It is 

 well known that, during flowering, the paleae are forcibly separated 

 by the swelling lodicules, and are held there for the space of anthesis. 

 The lodicules then shrink and allow the paleae to close. If now, during 

 the period, an insect, attracted by the shining, sappy and turgid masses, 

 attacks them by biting or puncturing, the resulting reduction of turgor 

 is sufficient to allow the outer palea to close, which it does "with sur- 

 prising swiftness" (Hildebrand, fide Ludwig) thereby trapping the 

 offending insect. This action, Ludwig points out, disadvantages the 

 plant in curtailing the time during which the flower would normally 

 remain open. No compensating benefit seems to accrue. 



The trap of Utricularia, minute though it is, is compared in the 

 present account to a mousetrap. There are mousetraps and mouse- 

 traps however, from simple to complex in structure, from a 5 cent 

 dead-fall to an elaborate, automatic self-setting one, which catches 

 them as fast as they come. If to this should be added a disposal plant 

 (Prof. Tracy I. Storer informs me that such a mousetrap has been 

 invented) so that nothing is left at last but hair and bones, the com- 

 parison would be fairly complete, especially if the trap should work in 

 any position and at the same time under water. These are constructed 

 of rigid parts, while that of Utricularia is composed of soft, yielding 

 parts. Previous to 191 1, the Utricularia trap was thought to be rela- 

 tively simple: a soft "pitcher" or vesicle guarded by a simple check- 

 valve; now it is known to have two valves, a tripping mechanism, a 

 spring which opens the door (one of the valves) which then automati- 

 cally closes, barely to indicate the complexity of the mechanism, the 

 complexity and perfection of which are extraordinary. In 1891 Goebel 

 said that the Utricularias are "among the most interesting of plant 

 forms, whether we view them from the point of view of their morphol- 

 ogy, anatomy or biology." If this was true at that date, it is, because 

 of the added knowledge about the complexity of the trap, much more 

 true now, as indeed Goebel personally admitted to me in conversation. 



For my own edification I have attempted to indicate the structure 

 of a mousetrap which, as closely as may be, duplicates the trap of 

 Utricularia without, however, hoping for the reward for him who invents 



