144 NATURE TEACHING 



tion, the actual placing of the pollen on the stigma, and 

 fertilisation resulting from this, are two perfectly separ- 

 ate processes, and should be clearly distinguished. 



The other parts of a flower may be naturally absent, 

 or artificially removed, without hindering the formation of 

 fruit. They are not essential. Stamens and pistil are 

 essential, for without them no seeds can be formed. Not 

 only, too, must they be present, but unless the stigma 

 receives upon it some pollen, no seeds will be formed. 



Sepals and petals are of use in other ways. The 

 sepals usually protect the more delicate and important 

 parts when young. They cover the flower-buds and act 

 in a very similar manner to the scale leaves which pro- 

 tect the leaf-buds in many plants. The petals usually 

 make the showy part of the flower, and, as we shall see 

 later, are of great use in helping to attract insects. They 

 are aided in this by the sweet smell of so many flowers, 

 and also by the presence of honey, which is well known 

 to be very commonly present in flowers, and in most of 

 those already discussed is to be found in fairly large 

 amounts. 



To sum up, we find that in flowers the stamens 

 and pistil are essential to the production of seed. The 

 sepals and petals are not essential ; the former acting as 

 a protective covering to the young flower, and the latter 

 having other uses in relation to insects. 



Insects and Flowers. 



Still bearing in mind such a case as the cucumber, we 

 have next to discover how the pollen finds its way from 

 a staminate flower to the stigma of a pistillate flower, 



