226 A NATURALIST IN THE PACIFIC chap. 



Aspidium aculeatum, a characteristic fern of temperate latitudes, 

 seems at first to present a difficulty, which, however, proves to be 

 more apparent than real. Whilst it has been recorded from 

 Hawaii at heights of 6,000 to 9,000 feet, and from Tahiti at 4,000 

 feet, it has also been found in Fiji and Samoa ; but since it was 

 not collected by Seemann in Fiji, it can scarcely be common, and 

 Home seems only to have obtained it from the tops of mountains 

 in Vanua Levu at an elevation of 1,800 feet. 



Up to this point the non-endemic ferns and lycopodshave been 

 chiefly discussed. We will now briefly deal with the probable 

 cause of the relative preponderance of peculiar or endemic species 

 in Hawaii as contrasted with Fiji and Tahiti. In this respect the 

 Hawaiian islands, as remarked at the commencement of this 

 chapter, come into sharp contrast with the other two groups ; but 

 it would seem that the differentiation has rarely acquired a generic 

 value (see Note 66). In this respect the age of ferns is markedly 

 distinguished from the succeeding era, the age of the arborescent 

 Composite and of Tree-Lobelias, to which a large number of 

 peculiar genera belong. This, according to my view, is to be 

 attributed to the circumstance that whilst the dispersion of spores 

 by the wind is probably as active in our own time as it was in the 

 earliest stage of the floral history of Hawaii, the dispersion of 

 seeds by birds, to which the flowering plants in the main originally 

 owe their presence in this group, has been greatly influenced by 

 the various changes that have affected the migration of birds over 

 the Pacific, a subject discussed in later pages. 



Respecting the origin of the species of ferns and lycopods 

 peculiar to Hawaii, it is first of importance to quote the remarks 

 of Dr. Hillebrand on the subject. Speaking of the whole flora 

 (p. xxv), but evidently with the ferns more especially in his mind, 

 he says : — " Nature here luxuriates in formative energy. Is it 

 because the islands offer a great range of conditions of life ? Or is 

 it because the leading genera are in their age of manhood, of 

 greatest vigour ? Or is it because the number of types which here 

 come into play is limited, and, therefore, the area offered to their 

 development comparatively great and varied ? " It is deeply to 

 be regretted that sickness and death intervened before the author 

 was able to give to the world his matured views on the very- 

 important points here raised. Yet they are much the same 

 questions that man is ever putting to the life around him. There 

 is the same querulous note that we find in all, the question that 

 begins, the question that ends, and the reply that never comes. 



