182 H. B. GUPPY^ M.B.^ F.R.S.E.^ OX PLAXT-DISTETBUTION 



Xow we have no reason to assume that the winds are less 

 effective in carrying the spores of ferns and lycopods than they 

 were in the earliest epoch of the floral history of the Pacific 

 islands. On the other hand, with the flowering plants, which 

 depend almost entirely on hirds for their dispersal, the opera- 

 tions of the dispersing agencies over this ocean have been, as I 

 have shown in my book, alw^ays irregular, and are now for the 

 most part suspended, the results displaying themselves in the 

 far greater number of peculiar species. In the case of Hawaii 

 the contrast between the endemism of the flowering plants and 

 of the vascular cryptogams is indeed much greater than is 

 indicated by the proportions of peculiar species, since its flora 

 contains nearly thirty peculiar genera of flowering plants 

 against only one or two amongst the ferns and lycopods. 

 However, these islands of the Pacific only illustrate operations 

 of far greater antiquity in continental areas : but with the 

 insular floras we are better able to compare the eftectiveness 

 of the dispersing agencies and to eliminate many of the 

 disturbing factors of continental floras. 



In continental regions the bird has been only one of several 

 agents that keep the difterent areas in touch with each other 

 by transporting seeds. But in the stocking of the isolated 

 arcliipelagoes of the Pacific the influence of birds has been 

 predominant. However, seed-dispersal over that ocean is now 

 practically suspended, and the birds that once carried seeds 

 from group to group, having long since ceased to wander, are 

 now represented by distinct species in the several archipelagoes. 

 The plants once dispersed by them have responded to the 

 change and have differentiated in the various groups, so that 

 stranoe inland plants and strange forest birds go together in 

 the Pacific islands. The nature of the connection between 

 freedom of dispersal and specific dih'erentiation was well 

 brought out in the collections made by Beccari in Borneo.* 

 Thus" he found that whilst 30 per cent, of the numerous species 

 of Ficus were peculiar, as many as 85 per cent, of the palms 

 had not been found elsewhere, the explanation lying in the 

 " facile dissemination " of the species of Ficus by birds as 

 compared with the palms. 



Whilst plants as a whole have responded through tlie run of 

 the ages to the differentiation of climate, in the case of those 

 possessing edible fruits tlie bird has largely determined the 

 rate of the change. With the secular drying of tlie globe tlie 



* See the author's book on Plant- Dispersal, p. 504. 



