64 AGE AND AREA [pt. i 



to have determined their distribution thereon, in broad outhne. 

 When stated thus, it would appear to be almost axiomatic, but 

 for a very long time the simple effects of age upon dispersal have 

 been lost sight of, under the widely held view that distribution 

 was rapid, and that local species were either local adaptations 

 or Avere dying out. 



The Ceylon figures gave strong evidence in favour of Age and 

 Area, but confirmation of the most satisfactory kind was soon 

 obtained by working out the distribution of the flora of New 

 Zealand (127), employing north and south diameters of areas 

 occupied {i.e. in the direction in which the islands run), and 

 obtaining these by actual measurement. This flora followed the 

 law with great exactness, as a quotation of actual figures will 

 show. 



Further work was then carried out upon various other similar 

 phenomena, the conclusions already made being confirmed by 

 the Orchids of Jamaica, CalUtris (a Conifer) in Australia, and 

 the flora of the Hawaiian Islands. A study of the ferns there 

 and in New Zealand also gave the same result, showing that the 

 law was probably quite general. 



Breakwcll (13) studied the grasses of Australia, and found 

 that while the species of very wide distribution showed an 

 average rarity there of 3, those confined to Australia and New 

 Zealand or Asia showed 4-1, and those confined to Australia 

 only an average rarity of 4-6, the figures agreeing exactly Avith 

 those already given. He also found that the genera showed the 

 same thing, and that it showed in Panicum alone, while several 

 of the larger genera showed a very close agreement. 



Taylor (105-6) has studied the endemics of Ncav York and 

 of the Bahama islands, obtaining results that harmonise quite 

 well with the general theory of Age and Area. In the latter 

 case, it was noticed that the difi'erence usually seen between the 

 distribution of the endemics and the wides was not nearly so 

 large as usual. This may be due to one or more causes; it may 

 1 Largely undoubted introductions of recent years. 



