TAKING UP OF POLLEN BY INSECTS. 245 



the pollen they have brought with them upon it, and may thus bring about cross- 

 pollination between the different flowers. 



In many cases insects visiting the interiors of flowers only get smeared with 

 pollen on the upper or the under parts of their bodies, or at particular spots merely, 

 and the adherence of the pollen ensues on their rubbing against the anthers which 

 are situated along the insect's route when it enters or leaves the flower. This 

 process takes place in a great variety of ways. In one case, the only part dusted 

 -with pollen is the proboscis; in another, the head; in a third, the shoulders or back; 

 in a fourth, the upper surface of the abdomen; in a fifth, the under surface of the 

 abdomen. There are instances also in which the pollen is only brushed off by the 

 peculiar collecting-brushes on the legs of bees which were spoken of in the last 

 chapter. Again, reference was made on page 153 to the remarkable case of the 

 small moth Pronuba yuccasella, which has the first joint of its maxillary palp 

 metamorphosed into an organ of seizure, and by means of that implement collects 

 the pollen from Fucca-flowers, makes it up into a ball and holds it fast in front 

 of its body (see fig. 240 5 , p. 157). 



If stamens, projecting out of the flower or situated on the floral threshold, serve 

 as a place for insects to alight on, as, for instance, in the flowers of Funkia, Viper's 

 Bugloss, Figwort and Monkshood (Funkia, Echium, Scrophularia, Aconitum), 

 pollen adheres to the underneath part of the insect's body the moment it settles, 

 or as it crawls towards the interior of the flower. In one of the species of Alpine 

 Eose (Rhododendron Chamcecistus) and in the Germander Speedwell (Veronica 

 Chamcedrys; see fig. 257 1 , p. 226), insects visiting the flowers, which are directed 

 laterally, grasp the exserted stamens with their front legs as if they were perches. 

 The stamens are arranged so as to bend downwards and inwards when touched, 

 thus they become almost instantaneously applied to the under surface of the insect's 

 body, which becomes smeared with the pollen. Great quantities of pollen adhere 

 to the under parts of insects in the case of Composite inflorescences. Shortly after 

 the opening of the corollas, the style bearing an external load of pollen is exserted 

 from each of the little tubular and ligulate florets composing the capitulum in this 

 group, and, owing to the fact that large numbers of these florets invariably open 

 simultaneously, numbers of styles laden with pollen project close together from 

 the discoid head. A largish insect settling on a capitulum may therefore be dusted 

 with the pollen of numerous florets at once. As he twists and turns about on the 

 disc of the inflorescence inserting his proboscis into one floret after another a lot 

 more pollen is brushed off on to the under surface of his body, and he finally leaves 

 the capitulum with an abundant freight. 



The transference of pollen to insects takes place in the Lady's Slipper Orchid 

 (Cypripedium) in a manner altogether peculiar. Here it is only one of the 

 shoulders of the visitor that receives the pollen. We will briefly describe how this 

 happens in the case of the European species (Cypripedium Calceolus). The floral 

 envelope of this Orchid (see fig. 267 l ) consists of six leaves, one of which is shaped 

 like a slipper, and has its deep cavity furnished at the bottom with hairs full of 



