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 Composite 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 Composite 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; aud 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 | 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, 
