168 THE FAIRY-LAND OF SCIENCE. 
knob ; and so the flowers become what we call 
" crossed," that is, the pollen-dust of the one feeds 
the ovule of the other. And just the same thing will 
happen if he flies from No. 2 to No. I. There the 
dust will be just in the position to touch the knob 
which sticks out of the flower. 
Therefore, we can see clearly that it is good for the 
primrose that bees and other insects should come to 
it, and anything it can do to entice them will be 
useful. Now, do you not think that when an insect 
once knew that the pale-yellow crown showed where 
honey was to be found, he would soon spy these 
crowns out as he flew along ? or if they were behind 
a hedge, and he could not see them, would not the 
sweet scent tell him where to come and look for 
them ? And so we see that the pretty sweet-scented 
corolla is not only delightful for us to look at and 
to smell, but it is really very useful in helping the 
primrose to make strong healthy seeds out of which 
the young plants are to grow next year. 
And now let us see what we have learnt We began 
with a tiny seed, though we did not then know how 
this seed had been made. We saw the plantlet buried 
in it, and learnt how it fed at first on prepared food, 
but soon began to make living matter for itself out of 
gases taken from the water and the air. How inge- 
niously it pumped up the water through the cells to 
its stomach the leaves ! And how marvellously the 
sun-waves entering there formed the little green 
granules, and then helped them to make food and 
living protoplasm ! At this point we might have 
