540 A NATURALIST ON THE " CHALLENGER." 



active agents in the fertilization of plants. I noticed, as has 

 been already mentioned, pollen attached in a similar manner 

 to a bird at Cape York.* Mr. Wallace conclndes that the 

 presence of these birds, as fertilizers, acconnts for the abun- 

 dance of conspicuous flowers in Juan Fernandez. 



There are very few insects in the island, according to the 

 observations of Mr. E. C. Eeed, and only one very minute 

 species of Bee. Flies, of which there are 20 species, form the 

 most prominent feature of the entomology of the island, t Some 

 fertilizers, either insects or birds, must act on a very comprehen- 

 sive and effectual scale all over the island, as follows from the 

 abundance of fruit yielded by various introduced plants. 



Strawberries, Cherries, Peaches, Apples, and Figs bear well ; 

 Strawberries and Peaches at all events very abundantly. The 

 Wild Peaches are spreading everywhere. These, the Cherries 

 and the Apples are possibly fertilized by the birds, but one would 

 hardly suppose that the Strawberries would be also thus pol- 

 lenized : though at a height of 9,000 feet in the Andes, I have 

 watched Humming-Birds, possibly the same species as that at 

 Juan Fernandez, hovering over the low mountain flowers, quite 

 close to the ground, where nothing like a bush was growing. 



It would be very interesting, if it proved to be the case, that 

 Humming-Birds have in this distant island adapted themselves to 

 the fertilization of our common garden fruits. Besides the fruit 

 trees, there are many introduced plants with well-developed 

 flowers which thrive in the island ; a Thistle is very abundant 

 and luxuriant, as if eager to remind travellers to what race the 

 world owes the immortal Selkirk, and a Wild Turnip is rapidly 

 spreading. Possibly the abundant flies take some share in the 

 fertilizing work. 



It must be remembered, with regard to insular floras, that a 

 plant which had developed showy flowers to attract certain 

 insects on some main land or other place where insects were 

 abundant, might, when transferred to an island devoid of insects 

 suitable to its requirements, nevertheless retain its gaudy flowers 

 little or not at all impaired, for an indefinite period, just as 



* See page 354. 



t A. E. Wallace, "Tropical Nature," p. 270-271. 



