3i8 A NATURALIST IN THE PACIFIC CHAP. 



tribe Cyrtandreae and of the whole order. The genera, as observed 

 by Mr. Clarke, are very continuous in their areas of distribution, and 

 in the tribe Cyrtandreae there are very few species that extend to 

 more than one region, whether on the mainland or in an oceanic 

 archipelago. In the Himalayas, he says, closely allied species of 

 Didymocarpus are confined to single districts, although there 

 appears no reason either in soil or climate why they should not 

 spread to the adjacent valleys. 



There is therefore, we may infer, nothing peculiarly character- 

 istic of insular floras in this prolific display of the genus Cyrtandra 

 in the Pacific, except that it is rather more pronounced in an 

 oceanic group than in a continent. The same general cause is 

 working alike in an island in mid-ocean, in a large continental 

 island bordering the mainland, and on the mainland itself. With 

 the Pacific Cyrtandras as with the British species of Rubus the 

 variability may be so great that the ordinary agencies of dispersal 

 fail to keep it in check ; and when, as in the Pacific islands, the 

 suspension of the activity of these agencies is complete, the 

 formative energy of the species knows no bounds other than 

 the determining limits of station. Our lesson from the Pacific 

 Cyrtandras is therefore this. The isolation of the oceanic 

 archipelagoes may not explain the endemic character of the flora, 

 but only the extreme degree to which the endemism is carried. 

 When a genus is in its prime, it can defy all the limiting condi- 

 tions imposed by similarity of station and by free and unchecked 

 means of dispersal, the essential marks of a species or a genus 

 having probably in their development little or no connection with 

 environment. 



The Cyrtandras of the Pacific Islands are most frequent where 

 vegetation is rank, as in moist woods, in humid valleys, and in 

 shady ravines and gorges ; but they may also occur in more 

 exposed and drier stations. They often grow gregariously, and 

 Schimper says the same of them in the Java forests (Plant- 

 Geography, pp. 291, 297). 



The fruit of the genus is described by Clarke as a fleshy or a 

 coriaceous berry. Almost everywhere in the Pacific groups the 

 berry is white and fleshy ; but it is noteworthy that out of the nine 

 Tahitian species where the fruit is particularised by Drake del 

 Castello, in two cases it is designated a capsule and in seven a 

 berry. It is in this connection worth remarking that in Malaya 

 other genera of the tribe often have capsular or dry and coriaceous 

 berries. The conspicuous white berries of the Pacific species would 



