254 Dr. J. D. Hooker on the Vegetation 



the very considerable number of widely diffused plants which are admirably 

 adapted for availing themselves of this means of transport ; though, on the 

 other hand, the exquisite care with which sea-fowl plume themselves must 

 not be overlooked, nor the slender chance there is of a seed remaining attached 

 to a body subjected to such violent motion and constant immersion as these 

 birds undergo. The plants which may have been thus introduced are species 

 of Tribulus, Siegesbeckia, Nicotiana, Dicliptera, Plumbago, Pisonia, Boerhaavta, 

 Poa ciliaris and Setaria Rottleri: all belonging to this section are ubiquitous 

 plants throughout the tropics. 



As no land-bird is common to the Galapagos and mainland of America, 

 this group is deprived of one very frequent means of transport, — the stomachs 

 of birds, which often receive seeds as the food, especially of the migratory 

 species ; these pass undigested from them in a locality far removed from 

 that where they were collected, not only with unimpaired vitality, but with 

 the process of germination accelerated. 



Man is the last agent to which I alluded : that he has been already active 

 is very perceptible from the fact, that Charles Island, the only colonized island, 

 contains the smallest proportion of peculiar plants, and numerically far the most 

 of these common to and probably introduced from the coast with cultivation. 



If the non-peculiar plants of the Galapagos then have been introduced from 

 the continent of America, it is the currents and winds that we must regard as 

 the agents ; of these, the winds are steady south-east trades, blowing from the 

 coast of Peru, by which the West Indian species cannot have been carried. 

 The currents are more variable ; and to these I would direct attention, and 

 have brought together all the information on this subject I could command, 

 from the voyages of the English and French in the seas between the Gala- 

 pagos and American shores. 



The principal oceanic current is a branch of the Antarctic or Southern Polar ; 

 it is a large body of cold water, which flows northwards from the icy regions to 

 the equator, parallel to, or perhaps impinging on the west coast of South Ame- 

 rica, and becoming deflected at its northern limit near the Galapagos, where 

 its course is between W. and N.W., flowing witli so great rapidity between 

 some of the islands as to render much interchange of seeds between such by its 

 means highly improbable. To its influence the canes, bamboos and palm-nuts, 



