174 THE HUMAN SIDE OF PLANTS 
It was long ago proved that close interbreeding 
produces degenerates in the plant kingdom. There 
are very few instances among high-class plants 
where perfect seeds have been produced without 
the ovules having been fertilised in the regular way: 
that is, by the transference of pollen from the male 
to the female flower. 
Among such plants as begonias, cucumbers, 
gourds, squashes, there are many flowers that are 
distinctly either male or female. If for any reason 
the proper insects do not exist in the territory 
where such flowers are to be raised, the flowers 
may be fertilised by carrying pollen dust from the 
male to the female by means of a feather or a 
dainty brush. But it is far more interesting to see 
the bees and butterflies happy in their work of dis- 
tributing pollen from flower to flower, yellow with 
the precious dust on their backs and heads! 
Plants have various schemes for securing a cross- 
fertilisation of their flowers. Some use the wind 
as an agent, others employ bees, butterflies, moths, 
snails, or even birds. Bird-pollination is a common 
occurrence in Brazil, where the profusely growing 
abutilon is fertilised by humming-birds. The 
Brugmansia and other flowers are fertilised in the 
same way. 
Flowers use their marvellous beauty, perfume, 
