ON PLANTS AND INSECTS. 



LECTURE II. 



IN the last lecture I endeavoured to show in a variety 

 of cases how beautifully flowers are constructed, so as 

 to secure their fertilisation by insects. Neither plants 

 nor insects would be what they are, but for the in- 

 fluence which each has exercised on the other. Some 

 plants, indeed, are altogether dependent on insects for 

 their very existence. We know now, for instance, that 

 certain plants produce no seeds at all, unless visited by 

 insects. Thus, in some of our colonies, the common Red 

 Clover sets no seeds, on account of the absence of hum- 

 ble bees ; for the proboscis of the hive bee is not long 

 enough to effect the object. According to Mr. Belt, the 

 same is the case, and for the same reason, in Nicaragua, 

 with the scarlet-runner. But even in those instances in 

 which it is not absolutely necessary, it is an advantage 

 that the flowers should be fertilised by pollen brought 

 from a different stock, and with this object in view, 

 insects are tempted to visit flowers for the sake of the 

 honey and pollen ; while the colors and scents are useful 

 in making the flowers more easy to find. 



Fortunately for us, bees like the same odours as we do ; 

 and as the great majority of flowers are adapted for bees, 



