130 



INTRODUCTION 



and the small trap withers and disappears, so that at length the poor flies escape 

 from their imprisonment and once more regain their liberty.' 



Hermann Miiller (Kosmos, iii, 1878, pp. 325-6) also considers that Calla palu- 

 stris (Fig. 43) represents a stage leading up to Pitfall Flowers, especially to those of 

 Arum maculatum (Fig. 44). Although it presents hardly any indication of transition 



Fig. 43. Calla palustris, L. III. Inflore- 

 scence, soinewliat reiiuced. IV. Single flower 

 in the first (9l coniiition. V. The same in 

 the second ( 5) condition, a', closed anthers; 

 a^, dehiscing anthers ; a', emptied anthers ; 

 St^ stigma. 



Fig. 44. Arum viaculatu-m, L., a Pitfall Flower. VI. An 

 inflorescence seen from the outside. VII. The same with flower- 

 trap cut open. VIII. The same on larger scale. IX. Cross-section 

 immediately above the entrance-groove : a, spatlie ; b, spadix ; 

 c, entrance-groove ; d, stamens ; ?, vestigial ovaries ; 7^ female 

 flowers. 



so far as the fly-trap is concerned, it is nevertheless one of those Nauseous Flowers^ 

 imperfectly developed, it is true to which the disagreeable odour entices Diptera 

 that are fond of decaying matter. Its broad, erect spathe, which is white internally, 

 and projects far beyond the inflorescence, acts not merely by way of attraction, but 

 also affords shelter against wind and weather to the little guests that are allured, 

 especially when it is still half rolled up. Arum maculatum offers such shelter in 

 a much safer and more comfortable way. For the spathe only opens above, so as 

 to permit the protrusion of the dark-purple end of the spadix, which serves both 

 as allurement and guiding-rod, while below it is closed, thus forming a pit that affords 

 a warm resting-place to visitors. The more exact description of the entire floral 

 adaptation is given in the second volume of this work. 



C. PiNCH-TRAP Flowers (Fpt). 



The family of the Asclepiadaceae is distinguished by the occurrence of peculiar 

 'clips' in their flowers, which consist of small, thin, hard plates of horn-like texture, 

 with an upwardly narrowing slit in the middle of their lower margin, and which bend 

 towards one another along their entire length in such a way that their edges lie close 

 together. To each such clip two pollinia belonging to two neighbouring anthers are 

 fastened right and left by means of two cords lying in the anthers. The clips grasp 

 the proboscides, claws, or bristles of insect visitors, and are forcibly torn away by 



