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 
Fic. 43. Calla palustris, L. Il. Inflore- Fic. 44. Arum maculatum, L., a Pitfall Flower. VI. An 
scence, somewhat reduced. IV. Single flower inflorescence seen from the outside. VII. The same with flower- 
in the first (9) condition. V. The same in trap cut open. VIII. The same ontarger scale. IX. Cross-section 
the second (4) condition. a}, closed anthers; immediately above the entrance-groove: a, spathe; 64, spadix ; 
a’, dehiscing anthers; a*, emptied anthers; c, entrance-groove ; d@, stamens; ¢, vestigial ovaries; 4 female 
st, stigma. 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. Priycu-Trap Fiowers (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 
