298 Scientific Proceedings, Royal Dublin Society. 



extremity, wliere it projects beyond the anthers. The median expansion 

 bears five ridges which lie at the bottom of the chambers formed by the 

 anther wings. The ridges are covered with high columnar glandular 

 cells whose function is the secretion of nectar ; they also secrete the clip, 

 which is found lying on them at the upper part of the ridge, and probably 

 the bands connecting the clip with the poUinia. The clip is a horny plate 

 whose inturned edges form a furrow narrowing upwards, the lower end of 

 the furrow being continuous with the slit between adjoining anther wings ; 

 from near its upper end on either side a homy band is given ofE whicli 

 embraces the lower end of the pollinium on the corresponding side. The 

 stigmatic surface of the style is on the under surface of the median expansion, 

 below the nectar ridges. The stamiual appendages have no nectar tissue. 



In these flowers, then, the nectar-secreting spots are not on the same 

 radii as the stamens, and we would, following Knuth, expect to find that the 

 clips clasp the proboscis of the pollinating insect, not the legs as in Asclepias. 

 This is doubtless the case. Tlie insect visitor reaches the nectar ridges by 

 inserting its proboscis into the sLit between two anther wings. This it will 

 most readily do attlie lower end of the slit where the edges of the wings turn 

 out a little. In withdrawing its proboscis, it will draw it- along the slit into 

 the clip where it will become firmly wedged ; and in withdrawing it further the 

 clip and bands witli attached poUinia must come too ; now in visiting another 

 flower tlie polliuia may be introduced into the slit and left there, thougli I 

 have not observed this. In two cases, however, I found the polliuia lying 

 at the base of the flowers, from which position their pollen-tubes had made 

 their way up through the lower part of the slit to the stigmatic chamber 

 (see Plate XXV., fig. 5). Possibly tlie chief function of the staminal 

 appendages is to scrape the polliuia off the proboscis of the visiting insect. 

 Tills would explain their curious shape. 



The secretion of nectar is very abundant, so much so that when the flower 

 opens a drop of nectar is extruded from tlie tip of the corolla. This nectar 

 is greedily taken by the Iridomyrmex living in the pitchers, and also by 

 another ant, Polijrachis acanlha, Sm., var. Kerrii, Forel, tliough the Irido- 

 myrmex often drives the Polyrachis, a much larger ant, away from the 

 flowers. I have had very few opportunities of observing the flowers of 

 D. rajjlcsiana, and tlie above ants are the only visitors to the flowers I have seen. 

 It is, however, a physical impossibility for either of them to effect pollina- 

 tion, as they have no means of reaching the column. Occasionally flowers 

 are found with a hole at the base of the corolla, evidently niade by some 

 insect in search of nectar ; but I have not noticed^ tliat such flowers were 

 fertilized, whereas it is not uncommon to find fertilized flowers with intact 



