118 
ing up the stems and eating away the green leaves 
above; and the cows and horses are pretty sure to leave 
the thorny plants well alone. It is easy to understand 
why we find thistle plants growing thickly in the pas- 
ture, which is nearly bare of everything else. Long ago 
these thistles clothed themselves in an armor of prickles, 
and ever since they have been successful in waging war 
against the cattle. 
Sometimes a tree will cover its lower part only with 
thorns. Why is this, do you suppose ? 
This is because only the lower branches are within 
reach of the cattle. Only these have any need of a suit 
of thorns. The wild pear, which grows in Europe, is 
such a tree as this. & pikes 
A stem that is covered with hairs, and also one that 
is sticky in spots, serves to protect its flowers from an 
attack by ants, or by other insects that might do them 
harm ; for these flowers, you remember, hold the golden 
dust which works such wonders when carried to another 
flower. And you recall, that, when bees go to plants for - 
the sweet stuff from which honey is made, they carry 
this flower dust from blossom to blossom. But if the 
sweet stuff is given up to greedy insects, then this good 
work is not done; for the bees get disgusted, and stop 
visiting the plants which do not take more pains to 
please them. And so oftentimes the plant covers its 
stem with hairs or with sticky drops, so that the med- 
dlesome little thieves cannot get up to the blossom at all. 
So if you pick a flower which leaves your fingers 
sticky, you must remember that the plant is only doing 
its duty in trying to please the bees. 
