Intro- — 7 — duction 



a mousetrap, promised, I believe, by Emerson. In this I am yielding 

 to the importunities of many of my friends, whose urgings I must as- 

 sume to be disinterested. I have, somewhat apologetically, relegated 

 the drawings and description (very necessary I fear) to an appendix 

 to the chapter on Utricularia. 



For such a mechanism we cannot find an analog among other 

 plants. Though it has moving parts, the property of irritability is not 

 used. Particularly, after the door opens, which it does only passively, 

 it instantly recovers its original position all in 1/33 second. Though its 

 movements are made possible by its turgidity, there is no change of 

 turgor — hence the instant reversibility of movement. But this again 

 depends on a structure which finds some analogy in the walls of anthers, 

 but only a partial one. Without further amplification we may regard 

 Utricularia as unique. 



It is not without interest to note that among the Lentihulariaceae 

 we find examples of the simplest traps (Pinguicula), the most complex 

 of the pitfall type, (in the lobster pot of Genlisea), and the incomparable 

 trap of Utricularia, whose only rival is that of Dionaea. Which of the 

 two is the more "wonderful" (I refer now to Darwin's statement that 

 he thought Dionaea the " most wonderful plant in the world ") will 

 perhaps be a matter of opinion, but the evidence seems to favor Utricu- 

 laria. 



How all these traps work and how we came to know about them, 

 it is the purpose of this book to tell. But I have not confined myself 

 to the traps, for it seemed necessary to present an adequate picture of 

 the plants as a whole. This was especially true of Utricularia, as, in 

 spite of many studies, a survey of the entire genus (and those of Poly- 

 pompholyx and Biovularia) has not been made since the 1891 publica- 

 tion of GoEBEL. No genus more fully substantiates the saying of 

 Caruel "La pianta cresce ciascuna alia sua idiosincrasia", for which 

 allusion I am indebted to Professor Goebel. The survey presented 

 seems to indicate with some fairness the extraordinary variety of form 

 and behavior of these plants, but necessarily as briefly as possible in 

 the interest of space saving. 



About the origin and evolution of the carnivorous plants, however 

 much these questions may intrigue the mind, little can be said, nor 

 have I attempted to discuss them. The evidence from fossils is meagre, 

 for these plants, even the most prolific of them, have seldom been pre- 

 served. A Utricularia {U. Berendii Keilhack) is recorded from the old- 

 diluvial of Oberohe (Engler and Prantl). No others, so far as I 

 know, have been recorded. The water lilies are recorded for the Ter- 

 tiary, and it is probable that Utricularia was contemporary. The fact 

 that they have originated at two or more distinct points in the phylo- 

 genetic tree is of major importance. How the highly specialized organs 

 of capture could have evolved seems to defy our present knowledge. 



J. G. Peirce (1926) remarks that the wide distribution of the car- 

 nivorous plants and the permanence of their peculiar morphological 

 and physiological characters mark them as descendants of ancient 

 forms, but we have to add that only some of them are widely dis- 

 tributed {Drosera, Pinguicula, Aldrovanda (Old World only) and Utric- 

 ularia) while others, though related in one taxonomic group or the 



