42 THE FERTILISATION OF FLOWERS. [CHAP. 



prisoners until the stigmas have passed maturity. 

 Each stigma secretes a drop of honey as a sort of 

 payment to the insects. The anthers ripen and dis- 

 charge their pollen, which falling to the bottom, dusts 

 the insects. The hairs shrivel up and set free the 

 prisoners, who are probably soon shut up in another 

 flower, which they fertilise with the pollen obtained 

 unconsciously from their first prison. This is the 

 only method in which fertilisation could possibly 

 take place in the Arum. Sir John Lubbock states 

 that sometimes more than a hundred small flies will 

 be found in a single Arum. 



In many other plants the same result is attained 

 by the anthers maturing before the stigmas, so that 

 an insect which had visited a flower with mature 

 anthers coming upon one with mature stigmas would 

 be almost certain to deposit some of the pollen 

 obtained from the former. Self-fertilisation in these 

 is out of the question. As an illustration, take the 



FIG. 48. 



FIG. 49. 



Common Pink of our gardens. Fig. 48 shows a 

 flower of this plant soon after expanding its corolla. 



