264 TAKING UP OF POLLEN BY INSECTS. 



petals which are inserted behind them. Honey is produced in abundance from 

 saffron-coloured swellings on the petals, and is to be found in the interior of the 

 flower sticking to those sides of the filaments which face the ovary. Both hive-bees 

 and humble-bees covet this honey and fasten on to the pendent racemes to obtain it. 

 Often, in the very act of laying hold of a flower, an insect inserts its forelegs into 

 it and touches the stamens; but even if this does not happen, the bases of the 

 stamens are sure to be touched when the insect introduces its proboscis to suck the 

 honey. The slightest touch administered to the lower third of a stamen's length 

 acts as a stimulus, and results in an alteration in the tension of the tissues, and in 

 a sudden backward movement or up-springing of the stamen. The anther is thus 

 caused to strike upwards against the insect, covering its head with pollen, whilst 

 the proboscis and forelegs are also besmeared, though to a less degree. 



The transference of pollen to the bodies of insects takes place in the Opuntia 

 in the same manner as in the Barberry. The comparatively large flowers of 

 Opuntia nana, which grows in Dalmatia and near Sion in the Rhone Valley, &c., 

 open at nine o'clock in the morning when the sky is clear. The fleshy four- 

 lobed stigma may then be seen crowning the thick conical style and forming 

 obviously the most convenient place for insects to alight on. The style rises out 

 of a pit which contains a copious supply of honey, and is surrounded by a large 

 number of erect stamens of difierent lengths. The dehiscent anthers are charged 

 with pollen of a crumbly consistency; the filaments have the lowest quarter of their 

 length coloured pale yellow and the upper part bright gold. If the golden region 

 of the filament is touched, it curves inwards, forming a semicircular and slightly 

 twisted bow, surmounting the honey-receptacle out of which the style rises. When 

 a bee visits the flower, it settles first on the large stigma, which projects above the 

 anthers, and then tries to clamber down to the honey. During this process contact 

 with the irritable portion of the filaments is inevitable, and the moment it occurs 

 the stamens that are touched bend over the bee and load it with their pollen 

 which is easily detached from the anthers. It is amusing to watch this phenomenon 

 and observe how quickly one after another the filaments bend over the insect, and 

 administer their blows as it crawls down. The bee is not much alarmed by the 

 infiection of the filaments, or by the taps it receives, but sufiers itself to be loaded 

 with pollen without making any fuss. It is able to brush it ofi" subsequently and 

 collect it in the "honey- baskets" borne on the tibiae of its hind- legs. As the 

 inflection of the stamens lasts at least until the insect leaves the flower, a further 

 supply of pollen is sure to be rubbed off when the bee begins to retreat. Usually, 

 when bees leave Opuntia flowers, they are dusted all over with the yellow pollen. 



Part of the pollen, in the case where the anthers belong to a mechanism of the 

 percussive type, is appressed and affixed to the insect's body, whilst part is brushed off 

 owing to the movements of the creature when it takes its departure from the flower. 

 In this respect the apparatus differs from contrivances of the explosive variety, 

 which are adapted to besprinkle or bespatter insects with pollen. The explosion is 

 due to a sudden up-springing of some organ, which may be the style, the filaments 



