THE WORK OF WINDS AND INSECTS 139 



So, unconsciously, he would have given his tiny help in 

 the world-wide work of Cross-Fertilisation. 



One of the chief friends of plants, as just stated, is 

 Wind. 



In some trees the catkins or stamen-flowers, with 

 their stores of pollen, grow long and hang low; while 

 the pistil-flowers, with their ovules, are perhaps higher 

 up ; so that the pollen from the former would not easily 

 reach the latter. And the reason why it should be so 

 we know. It is better for the trees that each -should pass 

 on its stores of golden dust to other trees, and should 

 receive what is needed for its own use from those others. 

 It is better, in fact, that each tree should not live a self- 

 centred and selfish life, merely to supply its own needs, 

 but that all should " freely receive and freely give." 



As their pollen is very light and dust-like, the most 

 gentle of breezes can lift the whole supply above the 

 tree-tops. Then, when it slowly descends, all the pistils 

 have a fair chance of capturing enough for their require- 

 ments ; while no tree is likely to receive pollen of its 

 own manufacture, since that would soon have been borne 

 away by the breeze. 



Pollen-grains are very tiny; and the amount con- 

 tained in each stamen is small ; therefore naturally we 

 do not realise what huge supplies are grown every year. 

 In the majority of cases it quits the little enclosing sac 

 in so gentle and unobtrusive a manner as to draw no 

 attention. 



But when a great number of trees of the same kind 

 grow together, and when they all shed their " dust " 

 at the same time, the effect is much more in evidence. 



