THE ENTOMOLOGIST. 227 



minute modifications of structure or of function many flowers 

 are adapted for partial insect- and self-fertilisation in varying 

 degrees, so that we have no difficulty in understanding how, 

 as the insects diminished and finally disappeared, self- 

 fertilisation may have become the rule, while the large and 

 showy corollas remain to tell us plainly of a once different 

 state of things. 



Another interesting fact in connection with this subject is 

 the presence of arborescent forms of Coraposilaj in so many 

 of the remotest oceanic islands. They occur in the Galapagos, 

 in Juan Fernandez, in St. Helena, in the Sandwich Islands, 

 and in New Zealand; but they are not directly related to 

 each other, representatives of totally different tribes of this 

 extensive order becoming arborescent in each group of 

 islands. The immense range and almost universal distri- 

 bution of the Compositae is due to the combination of a 

 great facility of distribution (by their seeds), with a great 

 attractiveness to insects, and the capacity of being fertilised 

 by a variety of species of all orders, and especially by flies 

 and small beetles. Thus they would be among the earliest of 

 flowering plants to establish themselves on oceanic islands ; 

 but where insects of all kinds were very scarce it would be 

 an advantage to gain increased size and longevity, so that 

 fertilisation at an interval of several years might suffice for 

 the continuance of the species. The arborescent form would 

 combine with increased longevity the advantage of increased 

 size in the struggle for existence with the ferns and other 

 early colonists; and these advantages have led to its being 

 independently produced in so many distant localities, whose 

 chief feature in common is their remoteness from continents 

 and the extreme poverty of their insect life. 



As the sweet odours of flowers are known to act in 

 combination with their colours, as an attraction to insects, it 

 might be anticipated that where colour was deficient scent 

 would be so also. On applying to my friend Dr. Hooker for 

 information as to New Zealand plants, he informed me that 

 this was certainly the case, and that the New Zealand flora 

 is, speaking generally, as strikingly deficient in sweet odours 

 as in conspicuous colours. Whether this peculiarity occurs 

 in other islands I have not been able to obtain information, 

 but we may certainly expect it to be so in such a marked 

 instance as that of the Galapagos flora. 



