CHAPTER VI 



AGE AND AREA 



The hypothesis which I have termed (123) Age and Area is not 

 a sudden discovery, but has grown up in my mind during a period 

 of about twenty years of work, in the study more especially of 

 the flora of Ceylon and its neighbouring countries. It will per- 

 haps prove of interest, therefore, to sketch this gradual develop- 

 ment, enlarging for the purpose a short account recently pub- 

 hshed (135). 



Going out to Ceylon in 1896, and remaining there till 1911, 

 I had constant occasion to refer to the volumes of Trimen's 

 Flora (37). There I gradually found, someAvhat to my surprise, 

 that the many species which are confined to that country [en- 

 demic to the island) were usually confined also to small areas 

 within it. Now at that time I held the view, then very usual, 

 that these endemics were specially adapted to the local con- 

 ditions, and it seemed very remarkable that they should be so 

 rare in those very conditions. If they were specially adapted 

 to Ceylon, therefore, it could hardly be to the general conditions 

 of the island (whatever those might be), but must be to strictly 

 local conditions within its area. Now this was the explanation 

 that was usually applied to the very numerous species that were 

 endemic in such regions as West Australia or South Africa, and 

 it was therefore clear that there were no differences between the 

 endemics of an island and those of the mainland, and that any 

 explanation that fitted the one would fit the other. 



Still more remarkable, therefore, did the facts appear, Mhen 

 I gradually began to study in greater detail the local distribu- 

 tion of the endemics, and found that they were not, as a rule, 

 confined each to one spot or small region characterised by some 

 special local pecuharity in conditions. Had this been the case, 

 they might have been supposed to have been evolved to suit 

 such spots, which in actual fact might be found without any 

 local species upon them. 



Coleus elongatus, for example, was confined to the summit of 

 Ritigala Peak (p. 14), a minute area, and was found now^here 

 else in the world; but C. inflatus, another endemic species, was 

 common all over the high mountain regions of the island. C, 



