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 
Fic. 48. 
Common Pink of our gardens. Fig. 48 shows a 
flower of this plant soon after expanding its corolla. 
