334 A NATURALIST IN THE PACIFIC chap. 



when the polymorphous species, having done its work of distri- 

 buting the genus, settles down and " differentiates " in every group ; 

 and this we see now illustrated in the genera Elseocarpus, Alyxia, 

 Peperomia, and others. 



The bulk of the genera of this period, of which only a few can 

 be mentioned here, hail from the tropics of the Old World through 

 Malaya. Thus Alyxia, Elseocarpus, Morinda, and Wikstroemia 

 are Malayan ; whilst genera like Eugenia, Peperomia, and Pisonia, 

 that occur in the Old and New Worlds, can similarly be traced to 

 the Asiatic side of the ocean by the distribution of their species. 

 Others again have their home in New Zealand like Metrosideros, or 

 in Australia, as with Dodonaea and Scaevola. None are exclusively 

 American. Some of the genera, as Morinda and Scaevola, have 

 littoral as well as inland species ; but, as shown in Chapter XIV, 

 there is rarely anything to suggest a derivation of the inland from 

 the coast species, both being, from the standpoint of dispersal, of 

 independent origin. 



About half of the plants have fleshy or sappy fruits (drupes and 

 berries) that would attract frugivorous birds, such as we find 

 in Xylosma, Elaeocarpus, Eugenia, Scaevola, Wikstroemia, &c., 

 whilst the others have often dry capsular fruits, with minute seeds 

 as in Metrosideros, or with larger seeds as in Dodonaea. Some of 

 them, like Pisonia, have fruits that excrete a viscid material that 

 causes them to adhere firmly to plumage. Birds both granivorous 

 and frugivorous have been actively at work ; and there are few 

 difficulties relating to dispersal connected with the genera, except 

 with such as Gossypium and Elseocarpus. 



I will adopt the method employed in the preceding chapter of 

 discussing in detail from the standpoint of dispersal some of 

 the genera that came most frequently under my notice, or in which 

 I am greatly interested, and of dealing briefly with some of 

 the rest. Those dealt with in other connections will not be 

 treated. 



El^OCARPUS (Tiliacese). 



This is a genus of trees containing, according to the Index 

 Kewensis, about 1 30 species, most of which are confined to tropical 

 Asia, including Malaya ; but a fair number occur in the Pacific 

 region, in Australia, New Zealand, and the islands of the tropical 

 Pacific, and the genus is also found in Japan. It will thus be seen 

 that Elseocarpus is not only a continental but also a typical insular 

 genus. It has reached not only some of the most isolated island- 



