84 THE EVOLUTIONIST AT LARGE. 



which sufficiently guards it against four- 

 footed depredators. Man, however, that 

 most persistent of persecutors, has found out 

 a way to separate the juice from the starch ; 

 and in St. Helena the big white arum is 

 cultivated as a food-plant, and yields the 

 meal in common use among the inhabitants. 

 When the arum has laid by enough starch 

 to make a flower it begins to send up a tall 

 stalk, on the top of which grows the curious 

 hooded blossom known to be one of the 

 earliest forms still surviving upon earth. But 

 now its object is to attract, not to repel, the 

 animal world ; for it is an insect-fertilised 

 flower, and it requires the aid of small flies to 

 carry the pollen from blossom to blossom. 

 For this purpose it has a purple sheath around 

 its head of flowers and a tall spike on which 

 they are arranged in two clusters, the male 

 blossoms above and the female below. This 

 spike is bright yellow in the cultivated species. 

 The fertilisation is one of the most interesting 

 episodes in all nature, but it would take too 



