88 ASSOCIATION OF ORGANISMS THE WEB OF LIFE 



passes below into a heart-shaped sticky knob (rastellum) that 

 projects into the cavity of the stigma. If now a fly alights on the 

 footstool and begins to lick up the nectar from the stigma, its 

 head will come into contact with the rostellum, and on leaving the 

 flower it will carry away the pollinia, which very quickly bend 

 forwards. When the fly visits another flower and thrusts its head 

 into the stigma, the sticky surface of this will catch and retain the 

 pollinia, another pair of which will become .attached to the head of 

 the insect, to be carried on in their turn to another blossom. 



The Lesser Butterfly Orchis (Habenaria bifolia, fig. 1080) is 

 a much smaller form native to Britain, and cross-pollinated by 

 Hawk - Moths. A number of whitish very fragrant flowers are 

 borne upon a long upright stalk, and there is here no platform 

 for the arriving guests, as these sip nectar without having to 

 alight. The nectar is contained in a slender spur, the length of 

 which corresponds to that of the unrolled proboscis of the moth. 

 As before, the departing guest carries away the two pollinia, 

 which then bend downwards, and converge together into the exact 

 position necessary to ensure their striking the stigma of the next 

 flower visited. In regard to these movements, and the somewhat 

 different ones made by the pollinia of other species, Darwin re- 

 marks (in Fertilization of Orchids]'. "A poet might imagine that 

 whilst the pollinia were borne through the air from flower to 

 flower, adhering to an insect's body, they voluntarily and eagerly 

 placed themselves in that exact position, in which alone they could 

 hope to gain their wish and perpetuate their race ". To this same 

 book of Darwin's are referred those readers who desire further 

 particulars regarding Orchids in the present connection. 



The different species of Honeysuckle (Lonicera, fig. 1080) are 

 also "moth-flowers", and exhibit three of the leading features 

 just detailed for the Butterfly Orchis, i.e. absence of an alighting 

 platform, pale colour, and marked fragrance. But, as in most 

 flowers except Orchids, the pollen is dust-like, and not aggregated 

 into pollinia. 



Insects are not the only animals by which cross -pollination 

 is brought about, for in some instances this work appears to be 

 discharged by Snails and Slugs, Birds, or Mammals. In our two 

 native species of Golden Saxifrage (Ckrysosplenium), snails and 

 slugs are said to be the agents. These plants live in damp places, 

 and possess groups of small greenish-yellow flowers, over which 



