I INTRODUCTION 5 



from the same plant, and after twenty-four hours added 

 some from a short-styled dark-red Polyanthus, which is 

 a variety of the Cowslip. From the flower thus treated 

 thirty seedlings were raised, and all these without ex- 

 ception bore reddish flowers ; so that the effect of the 

 plant's own pollen, though placed on the stigmas twenty- 

 four hours previously, was quite destroyed by that of 

 the red variety. In rare cases the pollen, if placed on 

 the stigma of its own flower, acts like a poison ! 



In most of our trees — Oaks, Beeches, Spanish Chest- 

 nuts, Conifers, and many herbaceous plants — the pollen 

 is carried by wind, and the plants are therefore said to 

 be anemophilous. In such cases there is a tremendous 

 waste of pollen. We all know the clouds produced by a 

 Scotch Pine. Wind-fertilised flowers, as a rule, are small, 

 green, and regular ; the pollen is dry and dusty, often 

 round and generally smooth. The stigmas are covered 

 with long hairs or papillae, thus off"ering a larger surface 

 to the pollen and increasing the chances of fertilisation. 



On the other hand, in the great majority of flower- 

 ing plants the pollen is carried from one flower to 

 another by insects. Such flowers are called entomo- 

 philous. They are generally large, and coloured — 

 yellow, white, red, or blue. They often emit scent and 

 produce honey, both of which serve to attract insects. 

 They also present great diversities of form and struc- 

 ture, often being irregular. The pollen is often angular, 

 with teeth, spines, or furrows, and more or less sticky. 



Bees and humble bees play a most important part 

 in carrying pollen from flower to flower. 



Every one knows how important flowers are to 

 insects; every one knows that bees, butterflies, etc., 

 derive the main part of their nourishment from the 

 honey or pollen of flowers ; but it is, on the other hand, 

 only recently that we have realised how much the flowers 

 themselves are dependent on insects. Yet it has, I think, 

 been clearly shown that if insects have been in some 

 respects modified and adapted with a view to the 

 acquirement of honey and pollen, flowers, on the other 



