CH. VI] AGE AND AREA 65 



be that the pecuhar conditions of the Bahamas, with their 

 sterile soil and considerable droughts, suit the endemics— which 

 must have been developed in them, and have had, as just ex- 

 plained, a strenuous struggle to become estabhshed, and which, 

 therefore, should be unusually well suited to the local conditions. 

 Although the parent species were able to survive there, the 

 endemics were probably better suited, and woiUd therefore be 

 able to overtake the former to some extent. 



Summary 

 Studying the flora of Ceylon, it was very soon noticed that 

 there were enormous differences between the areas occupied by 

 species of the same genus, some of which were endemic to the 

 island, some not, and this led on to a study of areas occupied in 

 general, when it was soon found that the endemic species occu- 

 pied, on the average, the smallest areas in the island, those found 

 also in Peninsular India (but not beyond) areas rather larger, 

 and those that ranged beyond the peninsula the largest areas 

 of all (again on the average). The two current theories about 

 endemic species— that they were local adaptations, suited to 

 special local conditions, and that they were relics — proved to 

 be incapable of explaining the facts when it was found, as was 

 ultimately done, that the areas occupied, both by endemics and 

 by widely distributed species, were arranged in a graduated 

 series, the first from many small to few large, the second in the 

 opposite direction. It was not possible to suppose that local 

 adaptation should exist in this graduated manner, nor that there 

 should be many relics at the final stage of dying out, and suc- 

 cessively fewer at all the stages leading iip to that. Some 

 mechanical explanation was necessary, and the only simple and 

 reasonable one was that the area occupied increased with age. 

 The actual quotation of the Age and Area hypothesis, as so far 

 developed, is given on p. 63. 



